BOSTON (CBS) – Former Massachusetts Governor Bill Weld is the first Republican to challenge President Donald Trump in the 2020 primaries.

Weld, who was once Robert Mueller’s superior at the Department of Justice in the 1980s, said he believes President Trump obstructed justice and Congress should see his full report.

“It just lays it out in gory detail,” Weld said of Mueller’s report released Thursday.

In an interview with WBZ’s Paula Ebben and Liam Martin, Weld said there is enough admissible evidence to sustain a conviction on appeal.

“Trying to get other people to lie to investigators, and I’m talking about senior intelligence officials and ambassadorial designees you know high ranking people and inducing and suborning perjury before sworn perjury and that’s a total obstruction of justice, and you know lying himself.”

Read: The Mueller Report

Weld says Trump needs to be challenged in 2020 because he has been “very destructive” to American priorities over the past two years. Despite Trump’s high approval ratings among Republicans, Weld thinks he has a chance to win the nomination when independent voters in states like New Hampshire are factored in.

“I think with all those crossover states and a lot of bumps in the road still to come, I think this is winnable nationally not just in New Hampshire,” Weld said.

Weld says he is an economic conservative and wants to cut spending. “I was rated the most fiscally conservative governor in the United States when I was here in office,” he said. “I don’t think Mr. Trump is an economic conservative by any stretch of the imagination.”

Weld served as Massachusetts governor from 1991 to 1997 before resigning to pursue the ambassadorship to Mexico.