NEW YORK (Reuters) – New York City Mayor Bill de Blasio, an unapologetically progressive Democrat who has been a frequent critic of the Trump administration’s policies, has decided to go after the president’s job. De Blasio, 57, launched his candidacy for president on Thursday with the central campaign message, “Working People First,” after months of speculation that he would add his name to a growing list of Democrats eager to take on President Donald Trump in the 2020 election. In a video released on Thursday, de Blasio returned to the theme of income inequality that animated his first mayoral campaign in 2013, when he emerged as a leading voice for the burgeoning left wing that has since reshaped his party. “People in every part of this country feel stuck or even like they’re going backwards,” he said in the video. “But the rich got richer.” The mayor, who is barred from seeking a third four-year term in 2021, has struggled to build a national profile, even as he has been eclipsed in the national consciousness by other progressives like U.S. senators Bernie Sanders and Elizabeth Warren, who are now his rivals for the presidency. He is scheduled to travel to the early-voting states of Iowa and South Carolina this weekend to begin campaigning. In the video, the mayor emphasized his record of progressive accomplishments, including universal pre-kindergarten, a $15 minimum wage and paid sick leave, all in a city that has a bigger population, more than 8 million, than most U.S. states. He also promised to stand up to Trump. “Don’t back down in the face of a bully,” he said. “Confront him and take him on.” Still, de Blasio faces an uphill battle to stand out among nearly two dozen Democratic contenders, including former Vice President Joe Biden and a long list of experienced politicians. Most New Yorkers appear unenthusiastic about de Blasio’s presidential aspirations. A Quinnipiac University poll in April found more than three-quarters of New Yorkers did not feel he should make a White House bid. His popularity took a hit after a federal investigation found the mayor made inquiries to city agencies on behalf of donors, though it cleared him of criminal wrongdoing. De Blasio has denied misconduct, saying he acted appropriately at all times. De Blasio has sharply criticized Trump on issues like climate change, immigration and policing. On Monday, he held a news conference inside Trump Tower to call on the Trump Organization to meet newly enacted emissions standards in their skyscrapers, or face significant fines. In a preview of what could be to come, the event drew scathing insults on Twitter from Trump’s two oldest sons, Eric and Donald Jr., who run the family company. The president retweeted a message from Eric Trump slamming de Blasio’s stewardship of his family’s hometown.