Representative Dean Phillips, a moderate Minnesota Democrat who has for months publicly argued that President Biden should not run for re-election, announced his candidacy for president on Thursday, setting up an underdog challenge for the Democratic nomination.
In an interview with CBS News, Mr. Phillips — who plans to officially launch his campaign on Friday in New Hampshire — argued that finding an alternative to Mr. Biden was essential because of polling showing the president at risk of losing to former President Donald J. Trump.
“I will not sit still and not be quiet in the face of numbers that are so clearly saying that we’re going to be facing an emergency next November,” he said. Late Thursday evening, he posted his campaign announcement on X, the site formerly known as Twitter, saying, “It’s time to put our country back together again.”
Mr. Phillips, a third-term congressman who represents a district that includes suburban Minneapolis, enters the race with long-shot odds.
The Democratic establishment and major donors have already lined up behind Mr. Biden, who raised $71.3 million with the Democratic National Committee and his joint fund-raising committee during the three-month reporting period that ended Sept. 30.
Mr. Phillips will also need to work fast to get his name on the ballot in several early-voting states. Already, he has missed the deadline to appear on the ballot in Nevada, the second nominating state on a new presidential primary calendar approved by the national committee this year.
Mr. Phillips, 54, has for months stressed his belief that Mr. Biden, 80, should face a serious primary challenge, citing the president’s age and low approval ratings as evidence that Democrats are eager for a new generation of candidates. (Several Republican candidates have made similar arguments in their bids against former President Donald J. Trump, who is 77.)
An heir to a Minnesota liquor company who also ran the gelato company Talenti, Mr. Phillips was first elected in 2018, as part of a wave of Democrats who flipped Republican-held suburban districts in a backlash to Mr. Trump. He stepped down from a position in Democratic leadership in the House this month as he weighed joining the presidential race.
Mr. Phillips will join two other primary challengers to the president: Marianne Williamson, the self-help author who unsuccessfully ran against Mr. Biden in 2020, and Cenk Uygur, the co-creator and co-host of the progressive talk show “The Young Turks.”
Another candidate, Robert F. Kennedy Jr., had initially planned to compete for the Democratic nomination but announced this month that he would instead run for president as an independent candidate.