South Bend, Indiana, Mayor Pete Buttigieg officially announced on Sunday his candidacy for the Democrat presidential nomination in 2020.

“My name is Pete Buttigieg. They call me Mayor Pete,” Buttigieg said. “I am a proud son of South Bend, Indiana, and I am running for president of the United States.”

Buttigieg, a Rhodes Scholar and Afghanistan war veteran, has explored running for president since January, and now joins a field of roughly a dozen-plus rivals to take on President Donald Trump.

The South Bend mayor has criticized President Trump’s slogan, “Make America Great Again” as a means of clinging to America’s past instead moving the country forward.

Buttigieg said in his announcement speech:

There’s a myth being sold to industrial and rural communities: the myth that we can stop the clock and turn it back. It comes from people who think the only way to reach communities like ours is through resentment and nostalgia, selling an impossible promise of returning to a bygone era that was never as great as advertised to begin with.

“The forces of change in our country today are tectonic,” Buttigieg said. “Forces that help to explain what made this current presidency even possible. That’s why, this time, it’s not just about winning an election — it’s about winning an era.”

A few months ago, the South Bend mayor was relatively unknown; now, Buttigieg has found himself in the upper echelons of the 2020 Democrat presidential polls.

A poll for the Pennsylvania primary released Friday found that “Mayor Pete” ranked in the top five in the state, while another poll released this week found that Buttigieg also ranks in the top five Democrats in the critical Iowa Democrat presidential caucus. Buttigieg even beat out Sen. Elizabeth Warren (D-MA) in the New Hampshire primary polls released this week.

These polls have shown that the Democrat upstart can stand with Democrat heavyweights such as Sens. Kamala Harris (D-CA), Cory Booker (D-NJ), and Warren.

A senior aide told CNN that he will focus on two topics during his campaign: the need for generational change and, striking a populist narrative, that he amounts to a different type of politician in an era when America wants to shake up the political establishment.

Buttigieg would be the first openly gay nominee of a major presidential party; Buttigieg marries his husband, Chasten in 2018.

Mike Schmuhl, Buttigieg’s campaign manager, said. “Pete’s a different kind of candidate, and we want to build a different kind of campaign. We don’t want to a top-down, consultant-laden operation. We want to be more like a startup, and we want to build in a smart way and a steady way.”