In 2013, the animal rights leaders helped undermine the mayoral campaign of Christine Quinn, boosting the chances of the eventual winner, Bill de Blasio.The last time there was a crowded race for mayor of New York City, a curious issue gained unexpected prominence: Just about every major candidate promised to do away with Central Park’s horse-drawn carriages, citing concerns over the horses’ safety.A notable exception was Christine Quinn, then the speaker of the New York City Council. Because of her stance, an animal rights group helped fund an “Anybody But Quinn” campaign that was credited with helping to topple her candidacy in 2013, paving the way for Bill de Blasio to become mayor.Eight years later, with horse-drawn carriages still rumbling through Central Park, that same animal rights group is making a return appearance in the 2021 mayoral race.The two founders of the group, New Yorkers for Clean, Livable and Safe Streets, or NYCLASS, announced on Monday their support for a new super PAC that will run television and digital ads attacking Andrew Yang, one of the Democratic front-runners in the contest.The ads were not the only curious development in the race: The office of the New York City comptroller, Scott M. Stringer, whose campaign for mayor appears to be losing steam, released an audit on Monday targeting the emergency food program established by a rival candidate, Kathryn Garcia, who has been rising in the polls. The audit raised concerns that he was using taxpayer dollars for political purposes.The audit and the anti-Yang ads were the most recent illustrations of how the June 22 primary, which is likely to determine the next mayor of this heavily Democratic city, remains in flux. Mr. Yang’s numbers have been falling, Ms. Garcia has gained ground, and Eric Adams, the Brooklyn borough president, is now thought to be in the lead, according to an Ipsos poll commissioned by Spectrum News NY1 that was released on Monday.The digital ads attacking Mr. Yang feature photographs of apparently ailing carriage horses lying on the street, and Mr. Yang’s “no” response on a questionnaire asking if he would support efforts “to strengthen welfare protections and increase the standards of care for New York City’s carriage horses.”The ads attacking Mr. Yang feature photos of apparently ailing carriage horses lying on the street.Andrew Seng for The New York TimesThe television ad makes no mention of animal rights, focusing instead on Mr. Yang’s qualifications.“What do we actually know about Andrew Yang?” the narrator asks in the advertisement, before launching into an unflattering biography of the former presidential candidate, describing him as “a prep school millionaire whose business career mostly failed.”The organization is spending about $200,000 for one week of ads, but is willing to spend about $1 million, according to its spokesman, James Freedland.The group’s leaders, Steve Nislick, a former real estate executive, and Wendy Neu, who runs a recycling and real estate company, declined interview requests. Jackie Kelman Bisbee, Ms. Neu’s sister and a film producer who is helping fund the super PAC, also declined to comment.In a statement, Mr. Nislick said that there was “no question that respect for animal rights goes hand in hand with respect for human rights.”“It’s clear that Andrew Yang is the wrong choice for mayor on both fronts,” he continued. “From supporting the abusive carriage horse industry to opposing tax increases on the wealthiest New Yorkers, Yang is simply unable and unwilling to stand up to the powerful forces that perpetuate cruelty in order to make a profit.”Chris Coffey, one of Mr. Yang’s campaign managers, spent years working as a lobbyist for NYCLASS and said he was taken aback by the group leaders’ decision to target Mr. Yang. Mr. Coffey accused the group of working behind the scenes with Mr. Adams.“This is the clearest evidence yet that Eric Adams is cutting deals with the same people who put Bill de Blasio in office,” Mr. Coffey said. “It’s time for a change from these sketchy unethical deals of the past.”A spokesman for Mr. Adams scoffed at Mr. Coffey’s suggestion that the borough president was involved in the ad campaign.“Absurd and sad,” said Evan Thies, the spokesman. “Apparently there are plenty of other people who don’t think Andrew Yang should be mayor.”A spokesman for Eric Adams, center, scoffed at the suggestion that the borough president was involved in the ad campaign.James Estrin/The New York TimesThe group’s founders donated generously to Mr. de Blasio’s mayoral campaign, but they also fought with him over his failure to actually ban the industry, as he had promised. Instead, Mr. de Blasio has moved the horse-carriage line from 59th Street into Central Park, and signed legislation limiting horse-carriage operations on particularly hot days..css-1xzcza9{list-style-type:disc;padding-inline-start:1em;}.css-3btd0c{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:1rem;line-height:1.375rem;color:#333;margin-bottom:0.78125rem;}@media (min-width:740px){.css-3btd0c{font-size:1.0625rem;line-height:1.5rem;margin-bottom:0.9375rem;}}.css-3btd0c strong{font-weight:600;}.css-3btd0c em{font-style:italic;}.css-w739ur{margin:0 auto 5px;font-family:nyt-franklin,helvetica,arial,sans-serif;font-weight:700;font-size:1.125rem;line-height:1.3125rem;color:#121212;}#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-family:nyt-cheltenham,georgia,’times new roman’,times,serif;font-weight:700;font-size:1.375rem;line-height:1.625rem;}@media (min-width:740px){#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-size:1.6875rem;line-height:1.875rem;}}@media (min-width:740px){.css-w739ur{font-size:1.25rem;line-height:1.4375rem;}}.css-9s9ecg{margin-bottom:15px;}.css-uf1ume{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-box-pack:justify;-webkit-justify-content:space-between;-ms-flex-pack:justify;justify-content:space-between;}.css-wxi1cx{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;-webkit-align-self:flex-end;-ms-flex-item-align:end;align-self:flex-end;}.css-12vbvwq{background-color:white;border:1px solid #e2e2e2;width:calc(100% – 40px);max-width:600px;margin:1.5rem auto 1.9rem;padding:15px;box-sizing:border-box;}@media (min-width:740px){.css-12vbvwq{padding:20px;width:100%;}}.css-12vbvwq:focus{outline:1px solid #e2e2e2;}#NYT_BELOW_MAIN_CONTENT_REGION .css-12vbvwq{border:none;padding:10px 0 0;border-top:2px solid #121212;}.css-12vbvwq[data-truncated] .css-rdoyk0{-webkit-transform:rotate(0deg);-ms-transform:rotate(0deg);transform:rotate(0deg);}.css-12vbvwq[data-truncated] .css-eb027h{max-height:300px;overflow:hidden;-webkit-transition:none;transition:none;}.css-12vbvwq[data-truncated] .css-5gimkt:after{content:’See more’;}.css-12vbvwq[data-truncated] .css-6mllg9{opacity:1;}.css-qjk116{margin:0 auto;overflow:hidden;}.css-qjk116 strong{font-weight:700;}.css-qjk116 em{font-style:italic;}.css-qjk116 a{color:#326891;-webkit-text-decoration:underline;text-decoration:underline;text-underline-offset:1px;-webkit-text-decoration-thickness:1px;text-decoration-thickness:1px;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:visited{color:#326891;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:hover{-webkit-text-decoration:none;text-decoration:none;}During his regular Monday morning media briefing, Mr. de Blasio said he hadn’t met or spoken with Ms. Neu or Mr. Nislick in “months and months, for sure.”In the years after the 2013 election, the New York City Campaign Finance Boards fined NYCLASS for making illegal campaign contributions, and the issue of horse carriages receded into the background.This year, four of the top eight mayoral candidates responded to NYCLASS’s candidate questionnaire. Only two of them expressed outright support for eventually banning the industry: Maya Wiley, Mr. de Blasio’s former counsel, and Dianne Morales, the former nonprofit executive. Mr. Adams selected “no” in response to the question about banning the industry, but then elaborated that he was “open to further discussion about prohibiting the operation of horse-drawn carriages.”Ms. Quinn, the target of the organization’s 2013 ad campaign, expressed disapproval of the group leaders’ new efforts.“What’s the horror movie where you can’t kill the monster and he keeps coming back?” Ms. Quinn said when reached by phone.Meanwhile, Mr. Stringer’s release of an audit targeting Ms. Garcia’s emergency food program prompted criticism that he was misusing the comptroller’s office for political gain.After the pandemic threw one million New Yorkers out of work, and it became apparent that New York City was facing a hunger crisis of historic proportions, Mr. de Blasio tasked Ms. Garcia, then the sanitation commissioner, with creating an emergency food program. At its height, it distributed 1.5 million meals a day.On Monday, Mr. Stringer’s office faulted the city for failing to adequately vet the background of a contractor whose owner had been convicted of obstructing the Internal Revenue Service.Scott M. Stringer, the city comptroller, released an audit targeting an emergency food program established by a rival candidate, Kathryn Garcia.Sarah Blesener for The New York TimesA spokeswoman for Mr. Stringer said the audit began last July, well before Ms. Garcia launched her campaign, and that the office evaluates whether an audit merits a news release based on the significance of the findings and recommendations.“The comptroller’s office has been diligently working to examine what went well and what didn’t during the response to the pandemic, and how to improve agencies’ emergency procurement procedures to quickly secure goods and services while mitigating the risks of squandering taxpayer dollars and contracting with unqualified or criminal vendors,” said Hazel Crampton-Hays, the comptroller’s press secretary.But Annika Reno, a spokeswoman for the Garcia campaign, was unconvinced.“It’s hardly a surprise that after Scott has spent his entire career in political office, that he would then use his office and taxpayer dollars to further his political career,” Ms. Reno said. “This is why New Yorkers don’t want another career politician as mayor, they want a public servant who gets things done.” More