What was the mayor of New York City doing in Iowa on Tuesday? Officially, he was raising money for a political advocacy group, Progress Iowa. 

"It is a very good time to be alive, and it's a good time to be a progressive, and we are here together at the beginning of a new era," Mayor Bill de Blasio said when delivering the keynote speech.

The mayor headlined a fundraiser for the organization in Des Moines on Tuesday night.

"Change can happen anywhere — anywhere — and it most certainly can happen here in Iowa," de Blasio said.

The trip is raising some eyebrows back home, and prompting questions about whether de Blasio wants to run for the White House.

The state is home to the country's first presidential nominating contest in 2020. De Blasio has said he just wants to help the Democratic Party nationally.

"I feel called to create progressive change anywhere I can," de Blasio said during a Q&A on Tuesday. "I am not running for president. I'm mayor of New York City for four years. We have term limits. I have 4 years and 13 days as of this moment. But I can walk and chew gum at the same time; I can be mayor of the city and still work on my core beliefs."

To illustrate that point, the mayor wrapped up the Q&A with reporters by pulling out a pack of gum, chewing a piece, and walking out the door.

He could not say goodbye quite as easily to protestors from back home. A city police union, Patrolmen's Benevolent Association, sent members to Des Moines to protest contract negotiations with City Hall.

Patrolmen's Benevolent Association First Vice President John Puglissi said they would follow de Blasio "wherever he goes" and make sure people know he's anti-labor.

The city's Transport Workers Union also attacked de Blasio in a full-page ad in the Des Moines Register.

"This is nothing new. Both these unions have done this kind of thing before," the mayor said. "It doesn't really make an impact on me."

De Blasio this is just the beginning for him, saying he intends to travel around the county, helping progressive causes, especially over the course of the next year.