Michael Avenatti said Tuesday he was “in” after suggesting a martial arts fight with Donald Trump Jr. for charity.

Avenatti made the proposition during a lunch at the Vanity Fair New Establishment Summit on Tuesday. He recommended a three-round mixed martial arts bout with the president's eldest son where proceeds would go toward charity.

Avenatti responded to an NBC reporter tweeting about the idea and said: “This would be for two great causes. I’m in.”

[Also read: Michael Avenatti: Don't blame me for Kavanaugh confirmation]

Avenatti has been outspoken in his criticism of President Trump. He is representing porn star Stormy Daniels, who has been embroiled in a legal battle with Trump this year over an alleged extramarital tryst more than a decade ago.

Trump has denied the affair. However, Trump’s personal lawyer Michael Cohen, who pleaded guilty to eight counts in August, paid her $130,000 in exchange for her silence on the affair. She filed a lawsuit earlier this year claiming the nondisclosure agreement she signed should be nullified because Trump didn’t sign it. She also sued Trump and Cohen for defamation.

Avenatti has been characterized as a “fighter” for his tactics, including by former members of the Trump administration, such as former White House chief strategist Steve Bannon.

“[Avenatti]'s got a fearlessness,” Bannon told HBO host Bill Maher last month. “And he’s a fighter. I think he’ll go through a lot of that field, if he decides to stick with it, like a scythe through grass.”