Former Rep. David Jolly (R-Fla.) on Monday said the national discussion about President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE's mental stability is a "grave conversation" that is "challenging for the country."

"This is a very grave conversation. It has been over 30 years since this nation had a conversation about whether or not our president was fit to serve," Jolly told host Nicole Wallace on MSNBC's "Deadline White House."

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His remarks come after a new White House tell-all by Michael Wolff, titled "Fire and Fury: Inside the Trump White House," claimed "every" White House staffer questions the president's mental health. Trump on Saturday tweeted in his defense that he is a "very stable genius," further fueling the discussion.

"There's an axiom in politics ... if you're explaining, you ain't campaigning," Jolly told Wallace.

"If you are talking about the president's mental fitness, you are not on message regarding his agenda nor the interest of the country," he added.

Jolly, who lost his reelection bid in November to former Gov. Charlie Crist Charles (Charlie) Joseph CristFlorida Democrat introduces bill to recognize Puerto Rico statehood referendum Anna Paulina Luna wins Florida GOP primary in bid to unseat Charlie Crist The feds should not spend taxpayer dollars in states that have legalized weed MORE (D), has repeatedly blasted Trump for exhibiting "risky behavior," complaining about GOP lawmakers and creating chaos for the Republican party.

The former lawmaker indicated in October that he preferred Democrats take the House in the midterm elections to serve as a great check against the president's power.

"There is no discernible Republican ideological agenda that is worth fighting for right now," Jolly said.

"But we do know that we have a president who very well might put this nation at risk, and this Republican Congress has done nothing to check his power. Democrats could [be a check], and we might be better off as a republic if they take the House in 2018," he said on MSNBC.

In a Sunday tweet, Jolly suggested he would vote for Oprah Winfrey if she ran in 2020 over Trump and Vice President Pence.