The father of former FBI Director James Comey said his son was fired by Donald Trump because the president was 'scared to death of him.'

The younger Comey 'didn't give him 100 percent loyalty and he demands that of pepole who work with him,' J. Brien Comey said Saturday to CNN's Miranda Green. '[Comey] said he would give 100 percent honesty, but not loyalty.'

And while Trump made headlines for calling Comey a 'nut job,' the ex-FBI director's father labeled the president 'crazy as a hoot,' and said he was rooting for his impeachment.

The father of former FBI Director James Comey (left) said President Trump (right) fired his son because he wouldn't pledge '100 percent loyalty' to the president

Former FBI Director James Comey will return to Capitol Hill after the Memorial Day holiday to give testimony before a Senate panel

The ex-FBI director was fired, according to his dad, 'because Jim tells the truth [while] Trump runs around lying most of the day.'

The 86-year-old also called his son's stacking 'a Trump deal.'

'Why he was fired, I think, is Trump changes every day,' he added. 'He had three reasons three days in a row.'

Brien Comey also described his son to CNN as a 'straightforward and honest guy.'

'[James] could have been subservient to Trump, [but I told him] he was not going to do that,' the father said of his son. 'Incidentally, I told him I thought he and Trump would testify side by side in front of these congressional committee. He just kind of laughed.'

Trump's firing of Comey teed off more than a week of negative headlines for the White House in the run-up to the president's first trip abroad.

The president axed Comey on May 9, but since then Trump told NBC's Lester Holt that the Russian investigation was on his mind when he decided to remove the top FBI official.

The New York Times then broke a story that said Trump pressured Comey to drop the investigation into former National Security Advisor Michael Flynn.

And most recently, the Times also reported that Trump had referred to Comey as a 'nut job,' when speaking to Russia’s Foreign Minister Sergey Lavrov and Russian ambassador to the U.S. Sergey Kislyak in the Oval Office the day after the ouster.

'I just fired the head of the FBI. He was a crazy, real nut job,' Trump said, according to a document summarizing the meeting, read to a reporter at the Times. 'I faced great pressure because of Russia. That's taken off,' Trump added.

While the younger Comey has stayed relatively quiet since leaving his top FBI post – though he will testify before a Senate committee after the Memorial Day break – the elder Comey had a lot to say about Trump.

'Oh my God, I think he should be impeached immediately – yesterday,' Comey said. 'He's a very incompetent guy. He's out of his league,' he continued, though noted the real chances of impeachment were 'a long shot.'

He also said he didn't vote for him.

'I think the man should be in a home quite honestly, he's crazy as a hoot,' Comey added.

The elder Comey also wasn't a fan of Hillary Clinton, who has blamed his son's letter with helping her lose the election, as it reminded voters of her ongoing email scandal.

'I am not going to tell you what I think of her,' Brien Comey said. 'We had lousy choices.'

As for how the younger Comey is fairing, now that he's on the outside, his father said he's 'doing fine.'

'He's a solid citizen, he has lots of opportunity,' the elder Comey said. 'It was a dumb thing to get rid of him. A loss for the FBI.'

Asked what James Comey thinks the future of the FBI investigation into Russia will be, his dad said he didn't know.

'We never talked about that stuff,' the elder Comey said.