William Weld, a former two-term governor of Massachusetts, will be challenging Donald Trump for the Republican presidential nomination.

Weld, who served as governor from 1991 through 1997, officially jumped into the presidential contest this month after considering making the race for several months.

“I really think if we have six more years of the same stuff we’ve had out of the White House the last two years, that would be a political tragedy and I would fear for the Republic,” said Weld. “So I would be ashamed of myself if I didn’t raise my hand and run.”

Weld developed a reputation as a socially liberal, economically conservative Republican.

He left the governorship after his nomination by President Bill Clinton to be ambassador to Mexico was torpedoed by conservative Sen. Jesse Helms of North Carolina. Weld ultimately left the Bay State and moved to New York to consider a run for governor in that state.

More recently, Weld left the Republican Party briefly in 2016 to serve as the vice presidential nominee from the Libertarian Party before offering a last-minute on-air endorsement of Democrat Hillary Clinton for president during an appearance on MSNBC host Rachel Maddow’s program.

Weld has a number of disagreements with Trump, both in domestic and foreign policy.

“I cut taxes 21 times when I was governor, but the difference is I cut spending before I cut taxes, and the president has not done that. So I don’t think it’s fair to say that he’s an economic conservative,” Weld said. “He certainly is an isolationist to a fault. He wants us to despise people from every other country and frighten the American public into thinking that they’re under siege from people in every other nation. That he calls being a nationalist. It really just means — to him it’s more important that we hate everybody else than it is that we love our own country.

“I declared my candidacy yesterday, April 15th, which is Patriots’ Day in Boston because — you know, I think being a patriot means you love your country and you love your country’s people,” Weld added. “And that’s clearly not true of Mr. Trump. He wants to divide his country’s people, ask: What’s the matter with white nationalism? It’s just the opposite of what we should expect from person in the Oval Office.”

In addition, Trump’s views on climate change are irresponsible, according to Weld.

“What you sometimes hear people say is, ‘I like the president’s tax cuts,’ and so do I, by the way, ‘but I don’t like his style.’ But it’s not style. When you’re as angry all the time and uncurious as this president is, it goes beyond style. It goes to policy and substance and I think he comes out in the wrong place.

“For example, the president insists that global warming is a hoax. But does he think those scientists who did those measurements are making money off the deal and lying about the results of the scientific examination? It just betrays a lag of homework and not really thinking ahead about what to do. You know, we’re going to have the white mountains with no snow. The oceans are going to rise. We’re going to have all our sea coast rearranged when that polar ice cap melts if nobody does anything about this. So I think to say, ‘It’s a hoax,’ and therefore it’s an excuse to doing nothing, I think that is utterly irresponsible. It’s not style, it’s substance.”

Weld, however, has his work cut out for him. Trump’s approval approaches 90 percent approval among Republicans, and Trump collected $30 million for his campaign during the most recent quarter.