[UPDATE BELOW] Unnamed sources tell The Amsterdam News and other outlets that mayoral candidate Bill Thompson will drop out this morning, just as the Board of Elections begins a hand-count of some 78,000 paper ballots, which make up approximately 11 percent of the vote. If true, the concession would be a sharp reversal for the former comptroller, who has repeatedly declared that he would not withdraw until all votes were counted.

"People want to see all the votes counted," Thompson told reporters yesterday during an appearance at the African-American Day Parade in Harlem. But the Times reports that "behind the scenes there were signs that he was weighing that possibility [of conceding] seriously, according to people close to the candidate."

After recanvassing all 5,049 voting machines used in last Tuesday's primary, Bill de Blasio's lead remained just over the 40 percent mark needed to avoid triggering a runoff. "We've said all along, we feel very confident about the result," de Blasio told ABC7. "And there's been a very respectful tone between both camps." Thompson clings to slightly over 26% of the vote.

Update 9:56 a.m.: Thompson's concession is all but confirmed. He's holding a surprise press conference on the steps of City Hall this morning at 11 a.m. Stay tuned.

Update 10:18 a.m.: The Wall Street Journal reports, "Gov. Andrew Cuomo, the state's top Democrat, is expected to attend the event at City Hall," and Capital New York points out, "For Cuomo, who avoided public appearances in the city during the primary, it's a bold entry that forestalls a potentially divisive run-off process, and projects his status as the central figure in the state's Democratic politics."