New York Mayor Eric Adams is expected to appear in federal court as early as Thursday before prosecutors from the Southern District of New York, two sources familiar with the matter said Wednesday night.

The charges were not immediately clear. Spokespeople for the FBI and the U.S. Attorney’s Office for the Southern District of New York declined to comment.

In a statement released Wednesday night, Adams said, “I always knew that if I took a stand for New Yorkers, I would be a target — and a target I was. If I am charged, I am innocent and I will fight this with all my strength and spirit.”

The Adams administration was already reeling from a series of high-level firings amid at least four ongoing federal investigations.

Adams, 64, a former NYPD captain and Brooklyn borough president, has repeatedly denied any wrongdoing.

One of the investigations is said to focus on whether Adams’ mayoral campaign colluded with the Turkish government to receive illegal campaign contributions from foreign sources. As part of that investigation, the FBI last year searched a Brooklyn home belonging to Adams’ top fundraiser.

Federal investigators are also investigating whether Adams pressured the city’s fire commissioner to approve a new building for the Turkish consulate despite security concerns.

Adams was still Brooklyn’s mayoral president when, shortly after winning the 2021 Democratic mayoral primary, he reached out to then-Fire Commissioner Daniel Nigro, according to sources familiar with the matter. Adams encouraged Nigro to evaluate a request from the Turkish government to use the building, which had not yet opened because fire officials had refused to approve the safety of its occupancy.

Adams’ phones were seized as part of the investigation, and FBI agents interviewed Nigro as a witness at least twice, sources familiar with the matter told NBC News. (Nigro declined to comment.)

Federal investigators this month searched the homes and seized phones of several top officials close to Adams. Police Commissioner Edward Caban, who was among those whose phones were seized, resigned on Sept. 12.

Authorities also seized the phone of Caban’s twin brother, James Caban, a former police officer who owns a nightclub security company. Federal investigators are investigating whether bars and clubs in Midtown Manhattan and Queens paid James Caban to act as a police liaison and whether those clubs then received special treatment from local precincts, sources familiar with the matter said.

There is also an ongoing investigation into corruption in the Adams administration and another federal investigation that led to a search of the homes of Adams’ former director of Asian affairs.

Before news of the federal charges broke on Wednesday, Adams attended a reception at the Metropolitan Museum of Art that was also attended by President Joe Biden. Adams also appeared on local television to answer questions live from viewers in New York.

The expected indictment puts the city government in a difficult position, said Douglas Muzzio, a former Baruch College political science professor who retired last year.

“Who’s in charge? What’s the direction of policy?” Muzzio said. “With so many people resigning, the city services are, in a sense, rudderless.”

Earlier Wednesday, Rep. Alexandria Ocasio-Cortez (D-N.Y.) called on Adams to resign.

“I fail to see how Mayor Adams can continue to govern New York City,” Ocasio-Cortez said on X. “The flood of resignations and vacancies threatens the function of government. Constant investigations make it impossible to recruit and retain a qualified administration. For the good of the city, he should resign.”

City Manager Brad Lander, who is running for mayor, also urged Adams to resign.

“Mayor Adams, like all New Yorkers, deserves a fair trial, the presumption of innocence, and his day in court,” Lander said on X. “However, it is clear that defending himself against serious federal charges will take up a significant amount of the time and attention needed to govern this great city. The most appropriate path forward is for him to resign so that New York City can regain the full focus its leadership requires.”

But in a videotaped statement released Wednesday night, Adams resisted calls to resign, saying any allegations against him were “completely false and based on lies.”

“Make no mistake,” Adams added, “you elected me to lead this city and I will do so.”