Former Massachusetts Gov. William “Bill” Weld announced Monday he is running against President Trump for the Republican nomination for president.

Weld revealed that he formed a presidential exploratory committee back in February, but Monday’s announcement makes his intra-party challenge official.

“In these times of great political strife, when both major parties are entrenched in their ‘win at all cost’ battles, the voices of the American people are being ignored and our nation is suffering,” Weld said in a statement provided to the Washington Examiner. “It is time to return to the principles of Lincoln – equality, dignity, and opportunity for all."

He added: "There is no greater cause on earth than to preserve what truly makes America great."

Weld, 73, is the first major Republican challenger to Trump’s presidency. He was appointed by President Ronald Reagan to serve as a U.S. attorney and served in that role from 1981 to 1986. Weld served for the following two years as the U.S. assistant attorney general for the criminal division under Reagan.

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Weld was later elected to two terms as the Republican governor of Massachusetts, serving from 1991 to 1997. He was reelected by the largest margin in the state’s history in the 1994 election.

His 2020 campaign highlighted how when he was governor, Weld was fiscally conservative, cutting taxes 21 times, and was an early proponent of LGBT rights.

This is not Weld’s first foray into national politics. He was former New Mexico Gov. Gary Johnson’s running mate on the Libertarian ticket during the 2016 presidential election.

As it became clear that Johnson was not likely to make much of a dent in the race between Trump and Democratic competitor Hillary Clinton, the former secretary of state, Weld began to draw comparisons between the two major candidates, and despite not technically endorsing Clinton, spoke in favor of her over Trump.

The Johnson-Weld ticket ended up taking in 3.8% of the national vote — the largest share of votes the Libertarian Party has ever received in a presidential election.

Weld changed his political affiliation back to the Republican Party in February, about the time he decided to start a presidential exploratory committee. Weld will face an uphill battle to unseat Trump, who holds a high approval rating among his Republican base.

Despite the odds, Republicans such as former Florida governor and 2016 Trump competitor Jeb Bush have urged a Republican primary challenge against Trump in 2020. There has also been speculation that former Ohio Gov. John Kasich, a moderate Republican, could run.

Maryland Gov. Larry Hogan’s name has also been tossed around as a potential primary challenge.

Along with Monday’s announcement, Weld’s campaign released a launch video lauding his accomplishments as governor and contrasting his tenure with controversial remarks the president has made, including a recording of the 2006 “Access Hollywood” tape in which Trump said he could grab women "by the pussy.”