Update, 4:05 p.m., June 12: As the tabulations round third and head home, San Francisco has gone old-school, poring over provisional ballots by hand. That level of scrutiny is due: They don’t call them provisional ballots for nothing. The city has to determine if these provisional voters were, indeed, eligible, then tabulate their ballots.

The Department of Elections counted 10,600-odd votes today — presumably the 3,000-odd remaining vote-by-mail ballots and a goodly chunk of the 14,000 outstanding provisionals. Mark Leno badly needed things to break inordinately his way.

That did not happen.

Instead, London Breed added 260 votes to her lead, and is now ahead by 1,861 votes, with 244,065 counted and, perhaps 8,000 left to count, depending on how many provisionals are tossed.

Regardless, the math is not adding up for Leno. Breed did better today than yesterday — and, once again, Leno could not up his percentage of first-place votes, netting only 20.5 percent in today’s batch.

In order to pull this out in stoppage time, Leno would have needed to dramatically increase that number, have Jane Kim do better as well, and, simultaneously, watch Breed flag.

That did not happen.

Counting should wrap up Wednesday. Leno still holds a mathematical possibility of victory. But, at this point, his chances of winning are asymptotically approaching zero.

Update, 4:05 p.m., June 11: New numbers from the Department of Elections are here. And if losing by less is the new winning, Mark Leno is doing that. After days of dropping hundreds of votes — if not more than 1,000 — to London Breed, today he fell behind by only 21 additional votes. And yet, he now trails Breed by 1,601 votes, with perhaps 3,000 mail ballots and the 14,000-odd provisional ballots to go.

The Department of Elections today counted around 9,000 ballots; Breed leads Leno 106,536 to 104,935 (50.38 percent to 49.62 percent).

Leno continues to pull down 67.8 percent of Jane Kim’s second-place votes (this takes into account the 7,210 of her 59,930 votes that didn’t transfer) Breed took 20 percent. But, as has been the case for some time, Breed succeeds in first-place voting. She now has 36.56 percent of the first-place votes, a healthy lead over Leno’s 24.87 percent and Kim’s 23.8 percent (Leno’s proportion has actually dropped since election night and Kim trails him by only 2,489 votes).

“This is relatively good news for Leno today,” says SF State political science professor Jason McDaniel. “If Breed had performed as she did over the last couple of days, she could have gained more than 100 votes. She only gained 21.”

On the returns counted today, Leno did slightly better than in days past, and Breed slightly worse, but Kim had a banner day. Can she catch Leno? “I have been thinking about that a lot,” admits McDaniel. “But it’ll be difficult. He’d need to just collapse.” If that were to take place, Breed would win by a fairly healthy margin, because a far greater percentage of Kim’s second-place votes are going to Leno than vice-versa.

Breed remains in the catbird seat. But “it’s inside the realm of possibility” for Leno to overtake her if the provisionals break sharply for Kim/Leno. “He’s treading water today. He could have sank. But this is the first real batch of vote-by-mail ballots that look a lot like election day as opposed to early vote-by-mail ballots [which trended sharply for Breed]. He’s still alive. But it will take some real shifts in the provisionals.”

And the district of origin where the provisionals are accepted — and where they aren’t — may be a factor too, if this draws ever closer. Tossed ballots from Districts 5 or 2 would hurt Breed; from District 8 would harm Leno.

This, again, is where lawyers might get involved, if it comes to that.

Update, 4:10 p.m., June 10: And we’ve got new numbers. And devastatingly good numbers they are for London Breed; she has added a a shade under 1,100 votes to her lead, giving her a 1,580-vote advantage over Mark Leno, 103,388 to 101,808.

That’s a 50.38 to 49.6 percent lead. And, while this is close, the path to victory for Leno has grown circuitously thin. The Department of Elections crunched 17,642 votes today, meaning fewer than 10,000 vote-by-mail ballots remain to go, along with some 14,000 provisional ballots. Thus far, the late drop-off vote-by-mail ballots have looked quite a bit like the early ones — meaning they’ve gone largely Breed’s way. Leno backers’ hopes that citizens dropping off their ballots at polling places would lean left — as day-of voters tend to — have not panned out. And, as such, barring a Warriors third-quarter-like barrage among the provisionals, Leno simply can’t make up the difference.

Leno continues to get better than two-thirds of Jane Kim’s second-place votes (that tally includes “exhausted” votes that didn’t go to anyone; among transferring votes he’s clocking around 77 percent). But he continues to flag in terms of first-place votes. Kim is outpolling him, and Breed today netted nearly 40 percent. Breed polls pretty well everywhere in the city — not great, but very good — and, seemingly, good enough. But, perhaps most importantly, she’s consistent geographically. Leno, however, is only polling well in District 8 — which rendered it a disaster Friday when the plurality of outstanding votes hailed from there and he still lost ground. Leno only pulled 22 percent in today’s batch. “Jane Kim is doing her part,” said SF State political science professor Jason McDaniel. “But Mark is just not getting enough first-place votes.”

Leno was taking more than 26 percent of first-place votes on election day to Breed’s 35 percent. “But he’s been below that every day since except one,” McDaniel adds. “His votes have just been too concentrated in that one area.”

If Leno was down by around 1,000 or 1,100 before the provisionals, McDaniel said, Leno still could eke it out — assuming 90 percent of the provisional ballots are deemed valid, and Leno equals or improves his election day numbers. Both of those scenarios are a stretch — and now the deficit is approaching 1,600.

“Those provisionals are going to be lopsided,” predicts McDaniel. But for Leno to prevail now “they’ll have to be super lopsided. And they’ll probably be more for Jane Kim and Mark does well. He could pick up 1,200 or 1,30o votes. But that might not be enough.”

Leno could gain 1,900 votes if this happens: Ninety-five percent of provisionals are accepted; Kim gets 33 percent of the first-place votes; Leno gets 28 percent; and Breed tumbles down to 31 percent. These are all anomolous numbers — including the gaudy 95 percent acceptance rate (state rates hover at around 80 percent acceptance. In San Francisco this year, a higher percentage might be deemed acceptable due to the advent of same-day registration — but, regardless, 95 percent is pushing it).

Knock on wood, lawyers won’t get involved, harking unpleasant memories to Florida in 2000 — but if a few provisionals here or there loom large in deciding the course of this election, it’s hard to see that not happening.

But Leno would have to surmount stiff odds for us to get to that point. “Mark needs a Hail Mary here,” McDaniel says, mixing our sports metaphors.

Crunching the numbers: in order for Leno to leapfrog Breed at this point, he’d have to gain ground via the provisional ballots at three times the rate he clocked on election night. That isn’t impossible. But it sure is improbable.

Update, 4:05 p.m., June 9: Last night — a Friday, and the night the Warriors won another championship — a Department of Elections worker could be seen on the city’s live-feed, tabulating votes, while sitting, barefoot, on the floor. And, as a result, we have new numbers on Saturday.

And, if you’re London Breed, they were worth waiting for. After spotting Mark Leno some 1,200 votes on the day of the election, she has caught and passed him to the tune of 498 votes: 94,771 to 94273. That’s 50.13 percent to 49.87 percent.

The Department of Elections crunched 20,060 votes today — 2,700 of which arrived via mail and 20,300 mail ballots dropped off at polling places — and Breed outpolled Leno by 644 votes.

Leno continues to feast on Jane Kim’s second-place votes. Factoring in the 6,513 of her votes that were “exhausted” and did not transfer to anyone, he still picked up 35,872 Kim votes — 67 percent. Breed received 10,693 (20 percent). Breed, however, continues to do well with first-place votes. She garnered 8,862 today, compared to 5,246 for Leno and 6,371 for Kim — marking another day when Leno’s own middling performance mitigated stronger numbers from Kim.

There are still some 42,000 votes remaining to be counted — and that includes around 14,000 provisional ballots. It is expected these will slant heavily toward Kim and Leno, so Breed needs to pad her lead. But, with the margins so tiny, even the slightest aberration from predicted trends could swing the race — and the chance for contentious behavior and lawyers getting invoved increases.

S.F. State’s Jason McDaniel, a political scientist, estimates that Breed will need to break into a four-digit lead to hold off Leno on the provisionals. But, he notes, she is now halfway there.

On the other hand, the winner of this election has already been decided — we’re just counting the votes now. So the appearance of momentum for one side or the other is illusory.

In order to win, McDaniel says, Breed needs another day resembling this one, then has to hope the provisional voting patterns aren’t even more heavily in favor of Kim/Leno than the election day totals were.

In order for Leno to win, he needs the next batch of vote-by-mail ballots to have more first-place votes for him. “He needs 26 or 27 percent as opposed to 22 percent, which is what he got today,” McDaniel says. He also needs to maintain or augment his high percentage of Kim’s seconds; Leno is besting the 67 percent his team felt he needed to get — but simply isn’t getting enough first-place votes. It would be helpful for Leno if remaining batches of votes hail from his stronghold of District 8 — but that’s yet to be determined.

If Breed builds up a lead of 1,000 or more votes before the 14,000-odd provisionals are counted, McDaniel feels it’d be an uphill climb for Leno to make up the difference. “It’d be doable,” the professor says, “but he’d just have to kill on those provisionals.”

Jim Stearns, a Leno consultant, posted data noting that many of today’s ballots hailed from the city’s west side — hardly Leno’s stamping grounds. But, Stearns admits, yesterday’s batch drew disproportionately from Leno’s favored District 8, and he still lost ground.

It appears to be heading down to the 14,000 provisional votes — of which the geographic data is not yet known — and the 6,000 election-day votes at City Hall, which skewed young/renter/other favorable Kim/Leno demographics. If these 20,000 votes don’t break heavily for Leno, Stearns admits, his candidate is in trouble.

Update, 4:10 p.m., June 8: We’ve got new numbers. And with 184,765 votes counted, Mark Leno leads London Breed by a scant 144 votes. The Department of Elections processed 19,807 votes today, and Breed whittled 111 votes off Leno’s lead. Leno currently has 83,667 votes (50.04 percent) to Breed’s 83,523 (49.96 percent).

If you factor in the 5,907 Jane Kim votes that were “exhausted,” then Leno received 67.2 percent of Kim’s votes — which is what put him in the lead and is keeping him in the lead (Breed received 9,269, which is 20 percent). Leno today received 72 percent of Kim’s seconds and Breed got around 19 percent. “These are the kinds of numbers Mark needs to win,” says S.F. State political science professor Jason McDaniel. And yet he lost votes. “This was a very good batch for Jane Kim — but London is increasing her percentage of first-place votes. This is showing Mark’s weakness in first-place votes. He’s been at 24, 25 percent. But London is doing better. Did two percentage points better today than yesterday.”

Kim, who pushed Leno across the finish line in first, is now keeping him from collapsing. Leno’s middling performance today in first-place votes mitigated a strong performance from Kim, and opened him up to a solid performance from Breed. Ominously, our number-cruncher sources placed 3,740 votes today from District 8, Leno’s base of support — and none of the other districts accounted for more than 2,699 votes. This is something of an ominous note for Leno, as is losing ground when Kim performs well.

“It’s like the fourth quarter of a basketball game,” said a local political strategist, “except it’s stretched out over two weeks.”

Some 50,000 vote-by-mail ballots remain to be counted, along with 14,000 provisional votes.

If these trends continue, McDaniel notes, Breed could have a three-figure lead on Leno by the time the provisionals are counted on Monday or Tuesday — unless, of course, a goodly portion of the outstanding votes also hail from District 8. The provisional ballots are expected to slant heavily toward Kim and Leno. This race, McDaniel notes with a nervous laugh, could potentially be decided by 100 or fewer votes. “Maybe it’ll be a tie,” jokes Jim Stearns, a Leno consultant.

“This sample seemed relatively proportional,” said Stearns. “In a pretty balanced sample of 20,000 votes, London climbed a little bit. So it’s going to be a nail-biter.”

We’ll have our next new tally on Saturday at 4 p.m. or thereabouts. Weekends are for the weak, it would seem.

Update, 4:15 p.m., June 7: After processing a mere 4,546 votes yesterday, the Department of Elections on Thursday counted 8,252 more. Yesterday’s votes shaved a mere 25 votes off Mark Leno’s lead over London Breed in the race for mayor. Today was a better one for Breed. Leno’s 1,121-vote lead shrank to a mere 255.  For those counting at home, Leno leads 74,424 to 74,169. That’s 50.09 percent to 49.91 percent.

“This is a pretty big shift,” confirms San Francisco State political science professor Jason McDaniel. “Yesterday, Breed improved by 0.02 percent. Today it’s by 0.31 percent. That’s 10 times better.”

But, McDaniel continued, Breed needs to not just catch up, but likely build a lead if she hopes to wrest the race away from Leno. After today, a shade over 80,000 votes remain to be counted. Of those, 14,000 are provisional ballots. And those, McDaniel says, will likely resemble the election-day votes and skew heavily toward Jane Kim, with her second-place votes going largely to Leno.

Of Kim’s 35,410 transferring votes, Leno received 27,194 and Breed 8,216. If you take into account the 5,413 votes that were exhausted, Leno received 63.4 percent of Kim’s votes, and Breed 22.6 percent. Yesterday, he got 69.2 percent of Kim’s votes, and Breed just 19.2 percent. “That’s the kind of difference Breed needs to win,” says McDaniel. “If this happens again tomorrow, she’ll be in the lead.” Breed today also gained many more first-place votes: 3,274 to Leno’s 1,841.

Department of Elections chief John Arntz has indicated this will be a prolonged counting period. He has unsubtly used plurals like “weeks” and “weekends,” indicating his team will be putting in 18-hour days (any more than that and the machinery may break down). Updates will come at 4 p.m. daily, including weekends. “Most” vote-by-mail ballots will be tabulated before Monday, and the provisional ballots will start to be tallied on Monday or Tuesday at the earliest.

The rule of thumb for San Francisco voting is that the later one votes, the more progressive he or she leans (with provisional ballots being the most left-leaning of all). That will be tested in this election; one new wrinkle is that this is the first contest in which voters could register at City Hall on the very day of the election. So, it’s consequential not just where the ballots counted today (and tomorrow and the next day) come from, but when they were cast.  “I care less about where the outstanding ballots come from than when,” political consultant David Latterman said at today’s SPUR post-election recap. “Somewhere there was an inflection point, where it went from London winning to Mark winning. I’ll bet it’s smack-dab in the middle, so this thing will be razor-thin all the way through.”

And, confirms the Department of Elections’ Gregory Slocum, “these are ballots that we received well in advance of Election Day. Anything we are processing thereafter was received on or after Election Day.”*

But location, location, location does matter. Leno consultant Jim Stearns posted on his Facebook page that “75 percent of the votes tallied today came from districts where Breed did best … only 25 percent of the votes counted today came from precincts where the Kim/Leno vote exceeded 50 percent.” Stearns also noted that Department of Elections data “shows that remaining ballots skew much younger in age (55 percent under the age of 50 vs. 34 percent under the age of 50 for ballots already counted).”

So, those are comforting trends for Leno. But Breed gained many votes today. There are a lot of votes yet to count and very few separating the candidates. Stay tuned.

*Re-reading Slocum’s statement, it appears that we are mistaken: The votes counted yesterday were received on or after election day. Our question was “Do we know when these votes were cast?” His answer was: “The votes that were counted today are VBM ballots that we are continuing to process, the first VBMs to be processed are represented in the initial preliminary report, these are ballots that we received well in advance of Election Day. Anything we are processing thereafter was received on or after Election Day. We are still able to accept and process VBM ballots that we receive through Friday due to CAEC’s E+3 provision (the ballots we accept must be postmarked on or before Election Day).”

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