Manhattan District Attorney Cyrus Vance Jr. has his first re-election challenger, with former Brooklyn Assistant District Attorney Marc Fliedner launching a write-in campaign for Vance’s post.

Vance, who has been in office since 2010, has come under scrutiny recently for a pair of investigations that were never brought to trial and the campaign contributions he received from players in the cases. The New Yorker, ProPublica and WNYC reported in a joint investigation that Vance’s office dropped an investigation into questionable real estate practices by Ivanka Trump and Donald Trump Jr. after meeting with Donald Trump Sr.’s personal attorney Marc Kasowitz, who later made a $32,000 campaign donation to Vance. Kasowitz also made a $25,000 donation before the meeting, which Vance promptly returned before the two met.

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And The New York Times reported that Vance’s office declined to bring charges after a 2015 sexual assault investigation into film producer Harvey Weinstein. Weinstein is a big donor to Democratic causes, and a lawyer he has employed, David Boies, has given thousands to Vance, including $10,000 in August 2015.

Vance has said that the evidence in both cases was insufficient to prove a crime. “None of the decisions revolved around campaign contributions at all,” he told the Times. He has since returned the contribution from Kasowitz, but not Boies, who Steve Sigmund, a spokesman for Vance’s campaign said had nothing to do with the sexual assault case, and was not representing Weinstein at the time. “We're confident that voters in Manhattan will continue to recognize [Vance's] record on November 7th,” Sigmund said.

Fliedner, a member of the Democratic Socialists of America, finished a distant third in the September primary for Brooklyn District Attorney, getting around 10 percent of the vote. He currently heads a private civil rights practice, and lives and works in Brooklyn, leading to questions about his eligibility for the Manhattan seat.

A request for comment from the New York City Board of Elections was not returned, but Fliedner said that, by his understanding, candidates must only be residents of New York City, not necessarily Manhattan. The Board of Elections tallies and counts all write-in candidates, no matter their residency. For example, “Barak Obama” got one write-in vote in the Brooklyn district attorney Democratic primary this year.

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“I am not in a position to mount a campaign complete with fundraising efforts and staff,” Fliedner said when reached by phone Wednesday. But he said he wanted to give Manhattan voters an option other than Vance.

“The expectation is that those who are interested in my candidacy will say ‘this is the kind of district attorney we’re looking for,’” he said.

The write-in campaign wasn’t Fliedner’s idea, but he agreed to it after the Twitter user known as @ShowUsYourWork encouraged him to run.

“Cyrus Vance is part of a grand tradition of corruption stretching back to Tammany Hall,” the user, who asked to remain anonymous, said. “This was a golden opportunity to oppose the machine politics that let Vance run unopposed.”

Vance is officially running unopposed, and his name will be alone on the ballot. But after information about the Trump and Weinstein cases was made public, some voters on social media have discussed other viable write-in candidates, including former U.S. Attorney Preet Bharara. Bharara, who lives in Westchester County, would likely be ineligible to take the seat if he were to win.

But any candidate running a write-in campaign, especially one with Fliedner’s low name recognition, would be an extreme longshot against Vance, who has the advantages of incumbency, an endorsement from the Manhattan Democratic Party and more than $900,000 in campaign funds.