It was a scene straight out of South Florida, circa Election 2000, only there were no hanging chads or butterfly ballots to obsess over.
With a hand recount of some 91,000 votes cast in a Democratic primary for a district attorney post in New York City just beginning on Monday, it did not take long for the first commotion to arise: a stray mark discovered on a ballot.
A crowd immediately gathered. Lawyers for the two leading candidates, Melinda Katz and Tiffany Cabán, surrounded the ballot, along with officials from the Board of Elections. A poll worker held the ballot aloft, as eyes peered in.
Was the mark an accidental stroke? Or deliberate? If the latter, the vote, which had been cast for Ms. Cabán — who is trailing Ms. Katz by only 16 votes — would be declared invalid.
The contest, for Queens district attorney, has local and national implications. It is seen as a measure of how willing Democratic voters are to soften the tough-on-crime policies that have long typified this working-class borough, and to follow the example of places like Boston and Philadelphia, where criminal justice reformers have won top prosecutor jobs.
The election also served as another test of the power of progressives to take control of the Democratic Party.
The Queens Democratic Party had been run by Joseph Crowley, the once-powerful Democrat who lost in an upset last year to Representative Alexandria Ocasio-Cortez.
Ms. Cabán, 31, a former public defender, drew support from Ms. Ocasio-Cortez, who encouraged small donors from around the country to contribute to Ms. Cabán’s campaign.
Ms. Katz, 53, the Queens borough president, was backed by local Democratic leaders and Gov. Andrew M. Cuomo, and collected endorsements and cash from major labor unions.
There were five other candidates on the ballot, but as the votes were tabulated on primary night, June 25, the race narrowed down to two, or, in Ms. Cabán’s eyes, just one: She declared victory after finishing with a lead of 1,100 votes, pending the absentee ballot count.
“They said we could not win,” she told supporters.
But the absentee ballots turned out to heavily favor Ms. Katz, reflecting support from older voters, and soon it was her turn to declare victory, by a margin of 20 votes, which subsequently was reduced to 16.
Things quickly turned exceedingly acrimonious, with the campaigns for Ms. Cabán and Ms. Katz accusing the other of suppressing votes.
The Cabán campaign and supporters accused the party establishment of invalidating votes for their candidate. A Democratic state senator, Alessandra Biaggi, took the charge to Twitter, posting dryly that “stealing elections is definitely the sign of a real leader.”
The Katz campaign fired back on the eve of the recount, with a statement accusing the other side of working “to undermine faith in the electoral system since election night.”
Amid all that rancor, the hand recount began shortly after 10 a.m. Monday, in a fluorescent-lit room deep inside a half-vacant retail colossus in Middle Village, Queens.
Board of Elections workers divided themselves among four groups of tables, each represented by a Democrat and Republican, joined by a volunteer from each campaign. Lawyers for both campaigns were also on hand for the inevitable disputes.
At one table, elections staff members struggled with the pronunciation of Ms. Cabán’s name. But for the most part, democracy seemed to be humming along, in the shadow of abandoned Kmart and Toys “R” Us stores. Votes were being recounted. Ill will and suspicion were kept mostly in check.
In a year in which politicians have fulminated about global cybertampering with elections, this recount was decidedly low-tech, with election workers tallying votes with handwritten red hash marks.
The ballot with the wayward mark was ultimately declared invalid by the chief clerk, over objections from the Cabán campaign. Another ballot, cast for Ms. Katz, was later invalidated. Workers quickly created manila folders for “objected ballots” to be decided later.
The challenges picked up slightly in the afternoon, but lawyers said some of the maneuvers were mainly to preserve those ballots for possible appeal.
Any disputes the two campaigns cannot resolve go to Judge John G. Ingram, who was temporarily brought in from Brooklyn to keep the process independent from the Queens Democratic Party.
The party is now run by Representative Gregory Meeks, who supported Ms. Katz, and has suggested that some parts of Ms. Cabán’s criminal justice platform go too far.
Ms. Cabán has said she would not ask for cash bail for any charges, including violent crimes, and that she would not prosecute sex workers or their clients.
Results from the recount are expected to take several weeks. Then cue the legal challenges, including some focusing on a portion of the more than 2,300 affidavit ballots, cast by people who went to polls and were not on a list of registered voters, that were disqualified by elections officials.
The Cabán campaign is focusing on more than 100 such affidavit ballots that were disqualified for technical errors in the affidavit, such as a registered Democrat not writing the word “Democrat” in a space for party affiliation.
State lawmakers last month passed a bill simplifying the rules and calling for election workers to count ballots where the voter’s intent is clear, even if not perfectly filled out, but the governor has not signed the bill into law.
“We will be in court if necessary to make sure every vote is counted,” vowed Jerry Goldfelder, a lawyer for Ms. Cabán.
But as the day wore on, tempers remained calm, former strangers at tables talked easily and neckties hung open — far from the accusatory climate of recent weeks.
The recount will include more than 350 ballots that did not register a vote for district attorney, although they were recorded as submitted to the voting machines. The voter may have improperly filled in the oval denoting his or her choice, or may have voted in other races on the ballot but not for district attorney.
The count did not include the affidavit or absentee ballots that were previously disqualified.
All this in a primary campaign in which just over 11 percent of eligible voters cast ballots — roughly 91,000 votes in a borough of 2.3 million residents.
The winner of the Democratic primary is heavily favored to defeat the Republican nominee, Daniel Kogan, in the November general election. Richard A. Brown, the previous district attorney, a Democrat, held the position for nearly 28 years before withdrawing in poor health earlier this year. He died in May at age 86.