VIDEO-'She's the devil!': Trump goes all in on Hillary-bashing

Donald Trump called his Democratic rival 'the devil' on Monday in a high-profile escalation of his campaign rhetoric – at precisely the moment he needed to change the subject.

Facing a four-day-long scandal over his criticism of the father of a Muslim soldier who died in combat, the Republican presidential nominee shifted gears.

Sen. Bernie Sanders, Trump told an overflow crowd at a high school in Mechanicsburg, Pennsylvania, 'made a deal with the devil' when he endorsed Clinton at last week's Democratic National Convention.

'She's the devil!' he added.

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'SHE'S THE DEVIL!': Donald Trump went all-in on Monday night as he said that when Bernie Sanders made an endorsement 'deal with the devil,' Hillary Clinton was the Satan figure

Trump has hinted at the insult before, saying Friday in Colorado that 'Bernie blew it. He sold his soul to the devil. He did.'

But Trump had previously stopped short of declaring that Hillary Clinton is, in fact, the Prince – or Princess – of Darkness.

By rallying around Clinton instead of standing on principle, the billionaire said, Sanders 'made a bad deal. He should have not made a deal. He would have gone down as [having] done something really important.'

'Once he made that deal, and believe me, he has buyer's remorse.'

'If he would have just not done anything – just go home, go to sleep, relax – he would have been a hero,' he said. 'But he made a deal with the devil. She's the devil! He made a deal with the devil. It's true.'

It's not the first time Satan has figured in this year's presidential election.

Sanders' campaign manager Jeff Weaver told CNN in April that it was Clinton who 'made a deal with the devil' by accepting millions in campaign cash from Wall Street banks.

'And we know the devil wants his money in the end,' Weaver said.

Weeks later, former House Speaker John Boehner told an audience at Stanford University that Texas Sen. Ted Cruz, who was then giving Trump a strong primary fight, was 'Lucifer in the flesh' and 'a miserable son of a b**ch.'

And Dr. Ben Carson, who may run the Department of Health and Human Services in a Trump administration, tried to tie Clinton to the devil two weeks ago during his Republican National Convention speech.

The former secretary of state, Carson said, was a disciple of far-left activist Saul Alinsky – who dedicated his book 'Rules for Radicals' to 'Lucifer, the original radical who gained his own kingdom.'