Former New York City Mayor Rudy Giuliani filed a defamation lawsuit Wednesday against President Joe Biden for calling him a "Russian pawn" during a presidential debate nearly three years ago.

Giuliani announced the lawsuit at a rambling news conference outside a courthouse in New Hampshire, where he filed to take advantage of the state's defamation laws.

The former mayor reiterated several familiar attacks against Biden and his son, Hunter, though he only sued the president -- despite the high bar for statements by public figures in a political setting to be found defamatory.

The move comes as Giuliani is facing his own legal exposure on several fronts and new questions about his ability to pay the lawyers representing him. Wednesday's news conference took place shortly after news broke that another lawyer, who has been representing Giuliani in the Georgia election subversion case, had withdrawn.

Asked if he was concerned about Giuliani's ability to pay his legal fees in this case, as his debts mount, Lou Diamond, one of the attorneys who appeared Wednesday alongside the former New York mayor, told reporters, "That is the furthest thing from my mind."

"When I say he's my friend, he is my friend. And he's the friend of the country. He is America's mayor," Diamond said.

CNN has reached out to the White House for comment.

Giuliani also addressed reporting from The New York Times that prosecutors from special counsel Jack Smith's office have asked about the former mayor's drinking habits -- and what Donald Trump knew about it while Giuliani served as the former president's personal lawyer.

Trump has been indicted in Smith's federal election interference case, and CNN previously reported that Giuliani is listed as co-conspirator 1 in that case. Giuliani has not been charged with a crime in that case.

"If I had an alcohol problem, and I could do all of that, I should be in the Guinness Book of Records," Giuliani said at the news conference in New Hampshire, where he listed off his accomplishments as a former federal prosecutor and mayor. "I do not have an alcohol problem. I have never had an alcohol problem."

At the center of Giuliani's new lawsuit are comments made by then-candidate Joe Biden during a presidential debate in Nashville in late 2020. At the time, Biden said Russia was feeding Giuliani false information to help Trump's chances of getting elected president.

"They're interfering with American sovereignty. That's what's going on right now. They're interfering with American sovereignty. To the best of my knowledge, I don't think the president's said anything to [Russian President Vladimir Putin] about it," Biden said at the time, referring to Moscow's efforts to undermine the US electoral process.

"His own national security adviser told him that what is happening with his buddy -- well I shouldn't, well, I will -- his buddy Rudy Giuliani," Biden added. "He's being used as a Russian pawn. He's being fed information that is Russian, that is not true. And then what happens? Nothing happens. And then you find out that everything is going on here about Russia is wanting to make sure that I do not get elected the next president of the United States because they know I know them, and they know me."

Giuliani said Wednesday he has been personally harmed by Biden's comments, which he called false.

In 2021, the US intelligence community assessed that Putin "had purview over the activities of Andriy Derkach," a Kremlin-linked former Ukrainian lawmaker, who met with Giuliani and repeatedly promoted anti-Biden disinformation.

Giuliani also insisted that the lawsuit was not retaliation for a lawsuit previously filed by Hunter Biden against Giuliani and his former attorney that asserted they violated federal and state computer privacy laws through their alleged efforts to hack his devices.

CORRECTION: The description of the news conference Rudy Giuliani hosted has been updated.