Ron DeSantis ended his presidential campaign on Sunday, leaving his rival Donald Trump on a glide path to bring the Republican primary to a close in New Hampshire. 

When the primary began, DeSantis was seen as the biggest intraparty threat to Trump.

With DeSantis out of the contest, the primary has become a two-person showdown between Trump and a struggling Nikki Haley.

DeSantis' capitulation is an important symbolic victory for Trump, who entered the primary as the pooh-poohed underdog after losing the White House in 2020. Trump, and many Republican voters, say the contest was rigged.

The rise and fall of DeSantis

Still, conservatives searching for an alternative to Trump had flocked to DeSantis, famously labeled "DeFuture" after thundering to re-election in Florida.

By the time he grudgingly called it quits on Sunday, DeSantis was greatly diminished, his political career under a cloud.

DeSantis campaigned as a younger, more disciplined, and electable version of Trump, but his campaign struggled to gain traction as DeSantis' lackluster personality and discomfort with retail politics became clear.

It didn't help that DeSantis' campaign - which consumed some $150 million in cash - was plagued with constant chaos and staff turnover.

Many of DeSantis' supporters, and DeSantis himself, blamed Trump's indictments for taking the oxygen out of the contest. But by the time DeSantis kissed the ring on Sunday, the outcome felt inevitable.

"If there was anything I could do to produce a favorable outcome - more campaign stops, more interviews - I would do it," DeSantis said.

New Hampshire showdown

After months of bitter back-and-forth with Trump, DeSantis endorsed his rival - the presumptive nominee - over Haley, who DeSantis said represented the "warmed over corporatism" of yesterday's Republican party.

"I signed a pledge to support the Republican nominee, and I will honor that pledge," he said.

For his part, Trump said he was "honored" to have DeSantis' support.

Polls on the eve of the New Hampshire primary show DeSantis supporters flocking to Trump as their second choice, casting doubt on the hopes of Never Trumpers that Haley will pull off an upset in New Hampshire.

It's hard to see how Haley could recover, even in her home state of South Carolina, if she stumbles in New Hampshire on Tuesday.

From there, it's likely just a matter of time before Haley is endorsing Trump, too.