Florida Gov. Ron DeSantis announced Sunday afternoon that he's suspending his presidential campaign and endorsing former President Trump, less than a week after failing to win a single county in the Iowa caucuses.

Why it matters: It's a flameout of epic proportions for a young, conservative culture warrior who — in the aftermath of his landslide re-election in 2022 — was widely viewed as Republicans' best hope for moving on from Trump.

• The GOP primary is now a two-person race between Trump and former U.N. Ambassador Nikki Haley, whose rise in the polls and increasing appeal to deep-pocketed donors came at DeSantis' expense.
• "I want to say to Ron, he ran a great race. He's been a good governor, and we wish him well. Having said that, it's now one fella and one lady left," Haley told supporters in New Hampshire, where her campaign faces a potential make-or-break moment in Tuesday's primary.

How we got here: Polls in December 2022 reflected DeSantis' immense promise as Trump's heir apparent, but months of unanswered attacks from the former president doomed DeSantis' campaign.

• DeSantis officially launched his presidential bid in May 2023 on a glitchy Twitter Spaces feed with Elon Musk, providing an apt metaphor for what would become a campaign dominated by online feuds and internal chaos.
• The scale of DeSantis' ambition was enormous: The Never Back Down super PAC promised to spend $200 million on an unprecedented field operation but devolved into a slow-motion train wreck as his polling endured a months-long free fall.
• DeSantis visited every county in Iowa and staked his candidacy on appealing to the state's conservative and evangelical base, only to finish 30 points behind Trump and just 2 points ahead of Haley.

Between the lines: Endless reports of infighting, staffing shakeups and strategic "resets" made DeSantis an easy target for Trump, who mocked his former ally relentlessly and in viciously personal terms.

• DeSantis began criticizing Trump more directly as desperation set in, but the inherent contradictions of the campaign — attacking the former president while trying not to alienate a GOP base that loves him — proved too difficult.
• "Trump is superior to the current incumbent, Joe Biden. That is clear. I signed a pledge to support the Republican nominee, and I will honor that pledge," DeSantis said in a concession speech posted online.

What to watch: Given the intense animosity that developed between DeSantis and Trump supporters — including calls to blacklist DeSantis allies from Republican politics — how Trump handles his rival's exit will be a key test of the GOP's ability to unify.

• Rep. Matt Gaetz (R-Fla.), a prominent Trump ally who also worked on DeSantis' transition team, said he would welcome the Florida governor back into the fold: "I hate when Mom and Dad fight."
• Rep. Bob Good (R-Va.), the DeSantis-supporting chair of the House Freedom Caucus, immediately endorsed Trump upon learning of his candidate's exit — potentially in an attempt to ward off recriminations.

DeSantis, for his part, seemed to recognize in comments last week that loyalty to Trump remains the organizing principle of the Republican Party:

• "You can be the most worthless Republican in America. If you kiss the ring, Trump will say you are wonderful."