Pete Buttigieg is ending his presidential campaign, according to a campaign aide.

The announcement will bring to an end Buttigieg's stunning rise from unknown mayor of Indiana's fourth largest city to the first major gay presidential candidate. His narrow victory in Iowa marked the first time a gay candidate and a millennial won a presidential nominating contest in US history.

And his rise from relative anonymity to Iowa caucus winner echoed Jimmy Carter’s victory nearly 45 years ago - an outsider with the promise of understated, honest political restoration.

But Buttigieg couldn't turn his successes in Iowa and New Hampshire - close finishes with or behind Bernie Sanders - into the broad coalition needed to secure a Democratic nomination. His struggles in reaching black and Latino voters dominated coverage for months, and resulted in poor showings in Nevada and South Carolina as the primary moved into states with more diverse electorates.

Facing tough results for a second week in a row, Buttigieg told supporters late Saturday night, "I am determined to earn every vote on the road ahead."

But on Sunday, after meeting with Carter himself and attending events to commemorate the Civil Rights movement in Alabama, Buttigieg decided to end his campaign.

Despite also being the first millennial candidate to win a presidential nominating contest - albeit with an incredibly narrow margin - his appeal resonated most with older Democrats, not peers and certainly not the next generation of voters, who prefer Bernie Sanders to all others. Buttigieg's actual political views remained somewhat opaque to the electorate - but over the course of the campaign, he shifted toward a considerably more moderate presentation and policy purview.

Buttigieg, in fact, modeled much of his approach on the Obama campaign, which galvanized millennial voters a decade ago. He spoke in the aspirational language about the day after Trump, projects the same kind of detached intellectualism, and centered his identity as the first gay candidate (and the perceived electoral risk that accompanies that identity) in how Barack Obama approached his own position as the party’s first black nominee and then the first black president. It didn't quite work the same for Buttigieg.

But his candidacy - especially in the muted response at times to its historical nature - marks off just how much has changed in the United States. When Obama ran for office in 2008, most Democrats and even he did not support marriage equality.