Rep. Dean Phillips, a Minnesota Democrat, withdrew from the Democratic presidential primary on Tuesday, ending the last significant primary challenge against President Joe Biden.

Phillips broke the news on The Chad Hartman Show, a Twin Cities radio show.

Phillips announced on Feb. 16 that he was laying off the vast majority of his campaign staff, after lackluster fundraising had created a cash crunch. He also canceled a scheduled event in Michigan on Feb. 18.

Phillips had promised to continue his campaign despite the layoffs, hoping to provide an option for Democrats worried about Biden’s electability to register their support for someone else.

Ahead of the New Hampshire primary, Phillips’ senior advisor, Jeff Weaver, had told HuffPost that strong performances in New Hampshire on Jan. 23 and in Michigan on Feb. 27 would establish Phillips as a credible alternative to Biden, and propel his campaign forward.

Phillips set a goal of picking up 20% of the vote in New Hampshire, a state where Biden was not on the ballot, but where Biden’s supporters mounted a successful write-in campaign. Phillips ultimately received about 19.7% of the vote, giving him grounds to continue onward.

The campaign’s decision to not seriously contest Michigan, however, suggested that Phillips had resigned himself to a symbolic candidacy only likely to be revived in the event of the Biden campaign’s sudden collapse.

Phillips’ candidacy was premised almost entirely on the argument that while Biden has been a very good president, polling showed he could not win in a general-election rematch against former President Donald Trump.

“Joe Biden is a good man. He is a fine man… He’s our president,” Phillips said to supporters at a party celebrating the results of the New Hampshire primary. “But I gotta tell you, everyone, he cannot win. The polls are saying he cannot win, his approval numbers are saying he can’t win. And the fact that an unknown congressman from Minnesota … said, ‘I’m going to come up here and run for president,’ just got 21% ― that says something too, my friends.”

Phillips, a moderate who belongs to the business-friendly New Democrat Coalition, also ran on enacting some policies that put him to Biden’s left, such as support for “Medicare for All.”

But he struggled to raise sufficient funds to compete for convention delegates beyond New Hampshire, where Biden’s absence gave him a unique opening.

Even after lending his campaign $4 million, Phillips, a vodka distillery heir and former chair of the Talenti gelato brand, only had $360,000 in cash on hand at the end of 2023.

Phillips’ failure to take off speaks to how effectively Biden and his allies have shut out dissent about the president’s continued viability within the Democratic Party.

At the same time, Biden has likely never faced more external skepticism about his ability to defeat Trump a second time.

In a report released early February, Special Counsel Jack Hur concluded that there was insufficient evidence to indict Biden for retaining classified documents after his vice presidency. But Hur’s rationale for not charging him included concerns that Biden’s advanced age and spotty memory of past events would make it difficult to convince a jury to convict him.

Seeking to quell doubts about his memory and overall mental acuity, Biden held a press conference later that day in which he exhibited some of the vigor and righteous indignation that many of his supporters had hoped to see. But his mistaken description of President Abdel Fattah el-Sisi as leader of Mexico, rather than Egypt, ended up dominating coverage of the event.

Biden subsequently declined to engage in an interview that would air before the Super Bowl, skipping an opportunity for mass engagement that has become something of an annual ritual among sitting presidents.

The sum total of those recent events, which also included Biden’s errant references to conversations with now-deceased former leaders of France and Germany, prompted influential New York Times columnist Ezra Klein, a long-time Biden defender, to announce on Feb. 16 that he no longer supports Biden running for a second term. Rather than endorse a specific candidate, Klein called for Biden to step aside and allow for the nomination to be settled in a contested Democratic National Convention in June.