Zach Iscol for Mayor? Not Anymore. Now He’s Running for Comptroller.

Mr. Iscol will be able to use the money he raised while running for mayor in the comptroller’s race, according to the campaign finance board. He has already probably met the lower threshold to qualify for matching funds for that race, pending an audit by that board, as has Assemblyman David Weprin from Queens, another candidate for comptroller.

Because the race for mayor is far from decided, voters may not treat Mr. Iscol’s departure from that race as a negative in the comptroller’s contest, said Bruce Gyory, a Democratic strategist.

“I don’t know if he’s the last, but he’s smart to be the first,” Mr. Gyory said. “The mayor’s race is so crowded with major figures that someone like Iscol would have been crowded out.”

There are several established candidates in the race for comptroller, including Mr. Lander, Mr. Benjamin, Mr. Weprin and Kevin Parker, a state senator from Brooklyn.

But it is unlikely that any can claim Hillary Clinton as a mentor, as Mr. Iscol can.

Mr. Iscol is friends with Chelsea Clinton, and his mother, Jill Iscol, has been an adviser to Ms. Clinton.

“I’ve known Zach Iscol for over two decades, and he comes at everything from the mind-set of ‘How do we bring resources and assets together to solve problems and address inequities,’” Ms. Clinton said in a statement. “He’s done it at the community level, the national level and in combat zones. He’s got a big heart and is indefatigable when he puts his mind to something.”

Mr. Iscol isn’t the only new entrant to the comptroller’s race. Michelle Caruso-Cabrera, a former anchorwoman for CNBC who unsuccessfully challenged Representative Alexandria Ocasio-Cortez in a Democratic congressional primary last year, filed paperwork to enter the campaign on Monday, her campaign confirmed.