Former Massachusetts Gov. Bill Weld announced Friday that he is launching a presidential exploratory committee, becoming the first Republican to officially look into challenging Trump.

Speaking at the Politics & Eggs breakfast in Bedford, N.H. on Friday morning, Weld said, “I think our country is in grave peril and I cannot sit quietly on the sidelines anymore.”

He went on to call Trump a “schoolyard bully” and “simply too unstable to carry out the duties of the highest executive office…in a competent and professional manner.” Weld added that Trump’s priorities are “skewed toward the promotion of himself, rather than to the good of the country.”

Weld will undoubtedly face an uphill battle in his race. Not only does Trump enjoy a high approval rating among Republicans, but also Weld himself only recently rejoined the party. After serving two terms as the Republican governor of Massachusetts in the early ‘90s, Weld later became New Mexico Gov. Gary Johnson’s running mate on the Libertarian Party ticket in the 2016 presidential election.

Weld reportedly plans to return to his Republican roots, however, running on an agenda of fiscal responsibility. He will only continue his challenge to Trump if he can raise enough money, reports The Washington Post. But even if he can’t, Weld aims to weaken Trump’s re-election bid.

While Weld is the first in the GOP to explicitly state his plans to challenge the president, he isn’t the first to express such sentiments. As recently as last November, reports suggested that former Ohio GOP Gov. John Kasich is also “very seriously” considering running against Trump in 2020.