Rep. Dean Phillips (D-Minn.) announced Wednesday that he's suspending his long-shot Democratic primary challenge to President Biden, ending a campaign that never gained any traction.

Why it matters: Phillips was an outspoken critic of Biden's re-election campaign, citing the president's age and polling showing Democrats wanted an alternative.

• "I am going to suspend my campaign, and I will be right now endorsing President Biden," Phillips said in an interview with WCCO Radio on Wednesday.

Zoom in: Biden trounced Phillips in every state's Super Tuesday contest.

• "Congratulations to Joe Biden, Uncommitted, Marianne Williamson, and Nikki Haley for demonstrating more appeal to Democratic Party loyalists than me," Phillips wrote on X on Tuesday night.

The big picture: Phillips, who filed paperwork for his presidential bid in October, repeatedly called for another Democratic candidate to jump in the race to challenge Biden.

• He was a strong supporter of a competitive Democratic primary and encouraged high-profile Democrats to enter the race, but launched his own bid when others would not.
• Phillips repeatedly said that voters craved an alternative to Biden and he called on the president to "pass the torch" to another candidate.

What he's saying: Phillips said while polling suggests many voters want an alternative nominee, "clearly and convincingly, Democratic primary voters have opined that I'm not that guy."

• "The choices are so clear. We only have two of them, and it's going to be Donald Trump or Joe Biden," he said. "And while indeed, I think the president is at a stage in life where his capacities are diminished, he is still a man of competency and decency and integrity, and the alternative, Donald Trump, is a very dangerous, dangerous man."

State of play: Phillips staked his bid on a strong showing in New Hampshire, where Biden did not appear on the ballot due to Democratic National Committee rules that made South Carolina the nation's first primary state.

• But Phillips finished a distant second in the state's primary, losing by more than 30 percentage points to the write-in votes for Biden.
• Biden easily won South Carolina and Michigan and largely dismissed Phillips' primary challenge to instead focus on key battlegrounds.

Between the lines: Phillips, a moderate three-term congressman, said in November that he would not seek re-election to the House in 2024.

• His support within Congress since mounting the bid has all but collapsed, underscoring the risks of challenging party orthodoxy.
• He said Wednesday that he does not plan to run for office in Minnesota again in the future, but will remain committed to encouraging public service and competition in elections.

The intrigue: Phillips, who had previously floated the idea of a third-party "unity ticket" with Republican Nikki Haley, said he was disappointed she didn't "immediately pivot" to an independent bid that could siphon support from Trump in November.

• "I do believe that only Nikki Haley is... probably the only American out of 350 million right now that could change the outcome of this race and ensure at least principle and decency remain in the White House," he said.

Go deeper: What to know about Democratic presidential candidate Dean Phillips

Editor's note: This story was updated with comments from Phillips.