A former director of the FBI has said he doesn't take any pleasure in the difficulties faced by Donald Trump.
James Comey was sacked by the former US president in May 2017, after ordering an investigation into possible Russian interference in the 2016 US election.
Mr Comey was nominated by Mr Trump's predecessor Barack Obama in 2013 for a 10-year term, having served three decades in law enforcement.
The White House cited recommendations from the US attorney-general and deputy attorney-general for the decision to fire Mr Comey - specifically referencing his handling of the Hillary Clinton e-mail controversy.
Mr Trump is facing 37 felony counts over documents found at his Florida home, as well as claims he obstructed justice and made false statements.
He has entered a plea of not guilty.
Mr Comey told The Pat Kenny Show it is 'painful' for the country that Mr Trump faces federal charges.
"I think it's embarrassing for the country," he said.
"It's good in the sense that it shows the American people that the rule of law still works, that the system operates to hold accountable without regard to your station in life.
"It's painful as a country that we have to show that that's necessary, and to contemplate the future where we may have one of the two candidates for president potentially be incarcerated at the time he's running for office.
"It's just painful for our country".
'Surprised when I was fired'
Mr Comey recalls being asked by Mr Trump to pledge his loyalty to him, one week into his presidency.
"Donald Trump figured out very early that I wasn't on anyone's team, and that I hadn't tried to help or hurt Hillary Clinton - and I sure hadn't tried to help him.
"Once he realised that I wasn't a political team player in that way, my tenure was doomed frankly.
"I was still surprised when I was fired...but I knew that there was an estrangement between us.
"He set up a dinner that I thought was a group dinner... and it turned out to be just the two of us at the end of his first week as president.
"He set up the dinner so he could ask me to pledge my loyalty to him personally".
Mr Comey said he underestimated how 'furious' Mr Trump was.
"I knew, that when I just stared at him and didn't give him an answer, and then avoided pledging my loyalty that there was going to be a real tension between us," he said.
"I actually convinced myself that that was good because it would keep him away from me; and the separation that the American people want, and have long wanted, between the president and the FBI director would be the result of that cold front.
"It turns out I didn't quite understand just how furious he would be that I wasn't going to be part of his inner circle," he added.