Hundreds of thousands of derelict Democrats avoided the polls on Election Day. Just a handful of them could have swung the race by marking their ballot for Katz or Cabán.

Instead, those non-voters will lack any direct impact on who earns the Democratic nomination — and likely wins the November general election — as the roughly 91,000 ballots cast in the primary undergo a full manual recount. The recount is set to begin after a Queens Supreme Court judge settles a dispute over 114 disqualified affidavit ballots on Tuesday. The recount could take up to three weeks to complete, election experts say.

Election night results had Cabán up by 1,090 votes. The early returns transformed her campaign event at a Woodside nightclub into a raucous celebration, and Cabán, a career public defender who promised to radically transform how people are charged and punished for alleged crimes in Queens, declared victory.

Heading into the July 3 count of those outstanding ballots, Cabán led Katz 34,104 votes to 32,905 votes.

But the count, conducted before monitors and attorneys from both campaigns, revealed a stunning reversal: Katz — a career politician who has also pledged to enact significant prosecutorial reforms — overcame the deficit and led Cabán by 20 votes. A vote differential of less than one-half of 1 percent triggers a recount, according to the BOE.

On July 5, the two campaigns reconvened at the BOE’s Forest Hills office to dispute another 2,300 affidavit ballots that were initially deemed invalid by the BOE. Affidavit ballots, also known as provisional ballots, are cast by people whose names do not appear on voter rolls for a variety of reasons: they may have never actually registered to vote, they may have been locked out by the intricacies of New York State’s arcane election laws or, as has already been the case in a few instances, the BOE may have made a mistake.

Cabán’s lawyer Renee Paradis successfully advocated to have six of those affidavit ballots validated. Five of the six votes went to Cabán and one went to Katz — a four-vote swing that reduced the differential to just 16.