Describing the US President is a threat to national security, David Jolly, who served as the representative for Florida's 13th congressional district between 2014 and 2016, suggested the country would benefit from Democrat success in next year’s midterm elections.
“We have a president who is known to be unstable," he told US cable channel MSNBC. "We have a president who is known to be risky when it comes to matters of national security."
Mr Jolly claimed leading Republicans in Congress are also rooting for their opponents in the hope of limiting Mr Trump's power.
He said: “I personally as a Republican in the past few weeks have wondered: Is the republic safer if Democrats take over the House in 2018?"
He added that he had recently raised the issue with a leading member of his party "and the remarkable thing is he had been thinking exactly the same thing."
He said: “This is a president that needs a greater check on his power than Republicans in Congress have offered. 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, and we might be better off as a republic if they take the House in 2018.”
Mr Trump’s presidency has “potentially very dangerous” consequences, the former congressman said.
Mr Jolly has previously described Mr Trump as an “ill-tempered, unqualified and at times dangerous leader of the free world”.
It comes amid reports that the president's allies fear he could be impeached if the Democrats regain control of the House of Representatives next year.
Major divisions have also emerged in the Republican Party ahead of next year’s elections.
Steve Bannon, who resigned as Mr Trump’s chief strategist in August, has said he is planning to field challengers to almost every Republican senator up for re-election next year.
He said: “Right now, it's a season of war against a GOP establishment.” The GOP is an abbreviation of "Grand Old Party", a term commonly used to describe the Republicans.
Mr Trump has also repeatedly criticised Senate Republicans for their failure to pass key pieces of his policy programme, including reform of Obamacare and a series of major tax cuts.