Mark Esper blamed Donald Trump for the GOP's poor results in the midterm elections. (Getty Images)

Donald Trump's former Defense Secretary slammed his former boss on Wednesday, calling him "unfit for office" just one day after the 45th President announced the launch of his 2024 campaign. “I think he’s unfit for office,” Mark Esper said of Trump in an interview for CNN.

“He puts himself before country,” the former Pentagon chief continued, adding, “To me, that’s shortcoming number one, and then I believe he has integrity and character issues as well.”

Esper went on to say that one of Trump's "character issues" is his difficulty telling the truth and that he believes Americans want a more trustworthy commander-in-chief. “I don’t think he’s an honest person. We saw the falsehoods that came out of his remarks last night … Americans need a leader they can trust,” Esper said.

The former Army officer, like many others who watched Trump's Mar-a-Lago announcement, was critical of Trump's Tuesday speech. “I thought his remarks were very subdued and uninspiring,” Esper said.

The former Defense Secretary also blamed Trump for the Republican Party's failure to gain more seats in Congress and state legislatures during the midterm elections. “The election last week is an example that Donald Trump is incapable of winning elections,” Esper said. “He’s done more to help the Democrats than the Republicans.”

Esper, who was fired after Trump's loss in the 2020 election, urged Republicans and Democrats alike to find new party standard-bearers. “I think that it’s time for the Republican Party, and frankly, both parties, to move on to the next generation of leaders, and particularly leaders that can unify our country and get us back to a more normal governance where we treat each other with dignity and respect, and we work on policy issues and not personal attacks,” Esper said

He praised recent Trump foe, Florida Gov. Ron DeSantis, as one of the "next generation" of presidential candidates. “He did a great job in Florida. He brought more Hispanics on board. He appears to me to be the frontrunner,” Esper said.

“But I think we need to have a primary to see who emerges and who can really, again, rally Republicans, grow the base, and really reach to Independents out there across the country.”