The leading candidates for mayor of New York City barreled into a frenzied final day of early voting on Sunday, a swirl of primary campaign activity marked by creative retail politicking and deepening acrimony between the race’s presumed front-runner, Eric Adams, and the rest of the field.

While the campaign trail was studded with lighthearted moments — Kathryn Garcia did yoga in Times Square; Maya D. Wiley hula-hooped — there were also serious clashes stemming from Ms. Garcia’s late alliance with Andrew Yang, leading Mr. Adams and his surrogates to question the integrity of the election, with two days until the June 22 primary.

Allies of Mr. Adams, the Brooklyn borough president, went so far as to baselessly claim that the appearance of an alliance between Ms. Garcia and Mr. Yang amounted to voter suppression — even though such alliances are common in elections with ranked-choice voting.

This is the first mayoral election in New York City that is using ranked-choice ballots, allowing voters to support up to five candidates in order of preference.

Ms. Garcia, a former sanitation commissioner, made another appearance with Mr. Yang, a former presidential candidate, on Sunday, but insisted again that did not mean she was backing his campaign.

Rather, she suggested, their joint appearances, on campaign literature and in person, were a calculated attempt to get Mr. Yang’s voters to rank her second.

In contrast to a number of her rivals who began the day in church, Ms. Garcia started with yoga in Times Square, and then visited Zabar’s on the Upper West Side and a greenmarket near Central Park, a schedule that might resonate with many a well-heeled Manhattanite.

The schedule reflected the importance of Manhattan to Ms. Garcia’s strategy, but it also underscored her challenge: to draw voters from beyond Manhattan and Brownstone Brooklyn. She has openly acknowledged that her appearances this weekend with Mr. Yang represented one tactic to expand her support. She spent time later Sunday in the Bronx, the borough with the largest Latino population.

With early voting winding down Sunday evening in preparation for Tuesday’s primary, voters streamed into polling sites in the five boroughs.

As of Sunday evening, 192,000 New Yorkers had participated in early voting.

Among them was Tom Werther, a retired police officer who carries a gun and thinks crime is the dominant issue of the day. On Sunday, he turned up to vote at the YMCA in Rockaway, Queens, but his first choice for mayor was not Mr. Adams, a retired police officer who also carries a gun and thinks crime is the dominant issue.

It was Ms. Garcia who impressed Mr. Werther as “articulate” during a recent meet-and-greet nearby. He ranked Mr. Yang second, and Mr. Adams third.

The final day of early voting happened to coincide with Father’s Day. Mr. Yang, a father of two, could be found tapping into his natural exuberance while posing for selfies on Sunday morning in Forest Hills, Queens.

Throughout his campaign, Mr. Yang has seemed happiest when he has been campaigning in person, surrounded by selfie seekers — a testament to the national name recognition and powerful social-media game that he hoped would drive him to City Hall.

But as he withstood the natural scrutiny accorded to front-runners, his standing in the polls diminished, and his tone darkened. In recent weeks, he has spoken ominously about the perils of voting for Mr. Adams, someone whom Mr. Yang considers ethically dubious and who is now leading the polls.

On Sunday, Mr. Yang’s original, crowd-pleasing spirit, the one he exhibited while vowing to be New York City’s cheerleader, was again on display.

Matthew Rubinstein, 19, attributed his vote for Mr. Yang to that energy.

“You see Andrew Yang going here, Andrew Yang going there,” said Mr. Rubinstein, who grew up in Forest Hills. “He’s on my TikTok, he’s on my Instagram. He’s everywhere, you know? He’s just more for the people.”

Mr. Adams and his allies continued to voice concern that by aligning their campaigns, Ms. Garcia and Mr. Yang were trying to disenfranchise Black and Latino voters.

Outside of a church in the Bedford-Stuyvesant neighborhood of Brooklyn, Mr. Adams said it was disrespectful for Ms. Garcia and Mr. Yang to campaign together on Juneteenth.

“While we were celebrating liberation and freedom from enslavement they sent a message and I thought it was the wrong message to send,” Mr. Adams said. “Yes, Andrew, you are a person of color and the Asian community realizes that I am the strongest voice for people of color in this city.”

At a campaign stop in the Inwood neighborhood of Manhattan, Mr. Adams was asked to respond to the voter disenfranchisement some of his boosters have claimed and he declined, even though his campaign sent out the statements.

Mr. Yang and Ms. Garcia both disputed Mr. Adams’s assertion, and so did Ms. Wiley, who is Black. She said that candidates were going to make different decisions about strategy under ranked-choice voting.

“I will never play the race card lightly unless I see racism, and I’m not calling this racism,” Ms. Wiley said.

She also defended the ranked-choice voting system after Mr. Adams again raised concerns about it. Good-government groups praise the new system as an advance for democracy, by no longer allowing candidates to split the vote and by eliminating the need for costly runoffs. Mr. Adams has long condemned the new system and his allies filed a suit to forestall its implementation that failed in court. Many voters have also expressed confusion about the system.

Ms. Wiley, who supports ranked-choice voting, said Mr. Adams must be afraid of her momentum if he was complaining about the system.

“I believe that ranked-choice voting is better for democracy, period — whoever people vote for,” Ms. Wiley said.

For his part, Mr. Yang suggested he was in fact campaigning with Ms. Garcia to prevent an Adams victory. He has repeatedly cast doubt on Mr. Adams’s moral probity as the borough president has faced residency questions and scrutiny over tax and real estate disclosures.

Later in the day, the central argument of Mr. Adams’s campaign — that the rise in street violence necessitates someone with his level of experience in policing — appeared to hit home in a personal way. The campaign used Twitter to announce that one of its volunteers had been stabbed; a week ago, the campaign said that a handgun was discarded in front of Mr. Adams’s campaign office in Brooklyn after a fight.

Scott M. Stringer, the city comptroller, kept a relatively low profile on Sunday, though he did make an afternoon appearance with his wife and two sons on the Lower East Side of Manhattan, and again in the Park Slope neighborhood of Brooklyn.

Mr. Stringer’s campaign faltered after two women accused him of sexual misconduct from decades ago.

Still, as he stopped to talk to voters on Sunday, many of them greeted him enthusiastically, and he sounded optimistic about his path to victory.

“As you can see on the streets, the reaction is great,” he said.

Reporting was contributed by Emma G. Fitzsimmons, Katie Glueck, Michael Gold and Jeffery C. Mays.