Washington(CNN) Former Massachusetts Gov. Bill Weld ended his Republican presidential campaign on Wednesday after President Donald Trump won enough delegates to win the 2020 Republican nomination.

"I have decided to suspend my candidacy for President of the United States, effective immediately," Weld said in an email to supporters.

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The former Massachusetts governor was the first candidate to challenge Trump for the Republican nomination. Weld told CNN's Jake Tapper in April he would "fear for the Republic" if the President were reelected.

"Leading this movement is one of the greatest honors of my life, and I will always be indebted to all who have played a part," he said Wednesday.

"But while I am suspending my candidacy," Weld continued, "I want to be clear that I am not suspending my commitment to the nation and to the democratic institutions that set us apart."

Weld's long-shot bid was at one point focused on winning over moderate Republicans in New Hampshire. Trump won the New Hampshire primary in February with 85.7% of the vote, compared to Weld's 9.2%.

Weld had some national name recognition from when he was the vice presidential nominee on the Libertarian ticket in 2016 with former New Mexico Gov. Gary Johnson. He was governor of New Hampshire's neighbor, Massachusetts, from 1991 to 1997, and won reelection there with more than 70% of the vote.

Weld is a fierce critic of Trump, and, last April, he called for the President to resign. Weld wrote in an op-ed that Trump's "rampant dishonesty and paranoia render him incapable of serving as president."

"It's time to plant a flag," Weld told CNN in a phone interview in the fall about why he launched a presidential bid. "Otherwise I'm right there with everyone else saying, 'Gee, I love the emperor's new clothes.' This emperor doesn't have any new clothes."

Weld ran for Senate in Massachusetts in 1996, losing to John Kerry. He later moved to New York and in 2005 unsuccessfully sought the Republican nomination there for governor.

This story has been updated with more information about Weld's run and background.