Weld won a single delegate in Iowa, but had trouble competing with Trump's popularity among the GOP base. Weld was also hampered by Republican rules that use a winner-take-all formula to award delegates, including in his native Massachusetts.

Weld's exit from the race means Trump is now the party's presumptive nominee — though it was never really in doubt. Trump amassed the number of delegates needed to win the party's nomination on Tuesday night after polls closed in Illinois, Arizona and Florida.

"Nobody motivates our base more than President Trump, as evidenced by the historic turnout we've seen in state after state this primary season," said RNC chair Ronna McDaniel said in a statement. "[We] are thrilled to have President Trump as our party’s presumptive nominee once again."

Weld ran for vice president as a Libertarian in 2016, alongside former presidential candidate Gary Johnson. In the days leading up to the general election in 2016, Weld encouraged voters to choose Democrat Hillary Clinton over Trump. The former Massachusetts governor re-registered as a Republican in 2019 to run for president.

Announcing the end of his campaign, Weld thanked his "tens of thousands of supporters and donors."

"I am intensely grateful to all the patriotic women and men who have stood with me and supported me during the past eleven months in our effort to bring better government to Washington, D.C.," Weld said.