You need to get surrogates and win those local activists over so they don’t go with the other candidates. And you need to meet the money that isn’t available in New York City.

If people are going to write you a big check, generally they want to meet with you in person.

Does running for president enable Mr. de Blasio to do something that he couldn’t do otherwise?

In the 2016 race, he tried to have an influence on the presidential conversation without being a candidate. It didn’t quite work.

He may think that the way to do that this time is to actually be in the race. You saw that last time around with Bernie Sanders. He had far more influence as a candidate than you imagine he would have had if he tried to just have a political action committee and support some candidates in 2016.

Maybe that’s what Mr. de Blasio is doing.

Running for president also helps stave off the effects of being a lame duck. He has to leave City Hall at the end of 2021. Already you’ve had people talking about the next mayor’s race, and it makes the mayor seem a little less powerful.

What exactly is the influence the mayor wants to have? What does his fingerprint on 2020 look like?

That’s a good question. He’s focused on affordable housing, universal prekindergarten and early education. He’s also talked about universal health care.

The trouble for him is that a lot of his ideas have been taken up, and people go further now.

What would be the de Blasio signature issue to move the Democratic Party in a way that it’s not already moving? I think he has to answer that question.