Former Vice President Mike Pence has refused to endorse Donald Trump for a second term as he increasingly takes issue with the populist rhetoric Trump has employed on the campaign trail.

Appearing on Fox News’ The Story, Pence announced, “It should come as no surprise that I will not be endorsing Donald Trump this year.”

Pence and Trump’s falling out can be traced to the aftermath of the 2020 presidential election when the vice president refused to reject the disputed election results and send them back to the states, as was theoretically within his capacity as president of the Senate, reported Fox News. Pence claimed that he did not have such a right.

He stressed that he and Trump have had their differences on a range of issues and “not just our difference on my constitutional duties that I exercised on January 6,” per Fox.

Though Trump is now the presumptive presidential nominee of the Republican Party, Pence himself was at one point a candidate. Pence’s refusal to endorse Trump sets him apart from other major candidates — with the exception of Nikki Haley — who failed to dethrone Trump’s front-runner status in the Republican primary but gave the former president their endorsement once they withdrew from the race, including Florida Gov. Ron DeSantis and entrepreneur Vivek Ramaswamy.

Pence went on to accuse Trump of “walking away from our commitment to confronting the national debt” and of “shy[ing] away from a commitment to the sanctity of human life,” per Fox. He also accused Trump of a “reversal on getting tough on China,” referring to the bill moving through Congress that would compel China to divest from the popular social media app TikTok.

Trump said last week on CNBC, “Without TikTok, you can make Facebook bigger, and I consider Facebook to be an enemy of the people.”

“Donald Trump is pursuing and articulating an agenda that is at odds with the conservative agenda that we governed on during our four years, and that’s why I cannot in good conscience endorse Donald Trump in this campaign,” Pence explained, per Fox.

Pence has increasingly taken issue with some of the positions Trump has taken that have made him a champion of the MAGA movement. This Sunday on CBS’s Face the Nation, Pence explicitly rejected Trump’s characterization of those imprisoned as a result of their participation in the January 6, 2021, protests as “hostages.”

“I think it is very unfortunate that at a time that there are American hostages being held in Gaza that the president or any other leaders would refer to people that are moving through our justice system as hostages. It’s just unacceptable,” Pence said.