It's a role he is considering filling himself.

In a political scene unthinkable just months ago, Avenatti was the closing speaker at the Democratic Wing Ding in Clear Lake, Iowa, a traditional stop for presidential hopefuls. His remarks came after a tour through the early-voting state that included a visit to the state fair and meetings with key Democratic officials.

"What I fear for this Democratic Party that I love is that we have a tendency to bring nail clippers to gunfights," Avenatti told an enthusiastic crowd in the Surf Ballroom and Museum. "Tonight I want to suggest a different course. I believe that the Democratic Party must be a party that fights fire with fire."

He added, "When they go low, I say, we hit harder."

It was a reversal of former First Lady Michelle Obama's declaration at the 2016 Democratic Convention, "When they go low, we go high."

In an interview, Avenatti said: "At that point in time, for what she was speaking about, I think that was the right message. But as we sit here now, that approach clearly will not work."

Amid his growing profile, Avenatti continues to represent Daniels, whose real name is Stephanie Clifford. She has said she had sex with Trump in 2006, months after his third wife gave birth to their son, but Trump has denied it.

Days before the 2016 presidential election, Daniels was paid $US130,000 ($A178,010) to stay silent in a deal handled by Trump's personal attorney Michael Cohen. She is suing to invalidate the nondisclosure agreement.

Asked if Daniels would support his presidential bid, Avenatti said, "I think that she's very supportive of the idea."

Australian Associated Press