Former President Donald Trump's days of freedom are likely numbered, says one former federal prosecutor.

"I think the odds of a conviction are extremely high," Glenn Kirschner told Sky News Monday.

The 45th president has been accused in four criminal cases and racked up 91 counts that could deliver more than seven centuries in prison, court records shows.

Kirschner believes the weight of the evidence, particularly from those that are expected to testify as witnesses are "almost exclusively Republicans" with some that served as Trump's former cabinet members, former Attorney General Bill Barr and former Vice President Mike Pence.

"I believe the testimony we will see will come from a chorus of Republican voices," he said. "It makes it much more difficult for Donald Trump, a fellow Republican, to say 'they're all out to get me."'

Trump could face a stiff sentence if convicted for attempting to undermine the 2020 election and disrupt the peaceful transfer of power to President Joe Biden.

"I believe the judge and prosecution team understand that if you don't punish that dramatic wrongdoing," Kirschner said, "then you're giving the next aspiring dictator a green light to do it all over again."

Trump is facing both state and federal government conspiracy charges over his suspected attempts to subvert the election defeat.

He has pleaded not guilty.

Despite the legal troubles, Trump is flourishing as the frontrunner to reclaim the GOP presidential nomination.

However, if Trump were to suffer a conviction, a quarter of his own supporters believe he should be nixed as the Republican Party’s nominee, according to a New York Times/Siena College poll.