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, will announce his candidacy for president on Thursday, a campaign spokeswoman confirmed, after months of speculation that he would add his name to a growing list of Democrats eager to take on President Donald Trump in 2020. The mayor, who is barred from seeking a third four-year term in 2021, emerged in 2013 as a leading voice for the burgeoning left wing that has reshaped his party. But he has struggled in the intervening years to build a national profile, and his approval ratings at home have waned after several political setbacks. De Blasio will release a video announcing his run before appearing on ABC’s “Good Morning America.” He is scheduled to travel to the early-voting states of Iowa and South Carolina this weekend to begin campaigning. The mayor plans to emphasize 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. But de Blasio faces an uphill battle to stand out among nearly two dozen Democratic contenders, who include former U.S. Vice President Joe Biden and liberal icons like U.S. Senators Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts. Most New Yorkers appear unenthused 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 any 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.