But it is a sign of the opportunity available to any Democrat willing to aggressively confront Mr. Trump that Mr. Avenatti is being invited to such venerable gatherings as the Wing Ding. After all, there is no lack of veteran Democratic officeholders with all manner of conventional qualifications who are also hoping to receive invitations to such events. (The dinner will also include a more familiar brand of dark horse candidate: House members. Representatives John Delaney of Maryland and Tim Ryan of Ohio are attending.)

“We live in a different age,” Mr. Avenatti offered as an explanation for how this was even possible. “I think a lot has changed over the last eight to 12 years with the advent of social media.”

But then he quickly put aside punditry and returned to his central message, and what he said was the important lesson from 2016, when Mr. Trump steamrollered a group of Republican politicians before dispatching Mrs. Clinton.

“We don’t want another candidate that just has a lot of experience,” he said. “Democrats need to nominate somebody who can actually beat this guy.”

He would not name any such potential candidates, of course: Why share the spotlight with anyone else?

A California-based lawyer, Mr. Avenatti was quick to note that he spent his “formative years” in St. Louis, that his parents still live there and that he considers himself a Midwesterner.

And he said he will return to Iowa later this month.

As for the pornographic film artist who put him on the map — or screen — he said that “Stormy is 100 percent supportive” of his exploration.

“She knows these are dire times,” Mr. Avenatti said.