Rosie O'Donnell: 'Donald Trump Is Mentally Unstable'

Rosie O'Donnell is not backing down in her criticism of Donald Trump.

In a New Years Day tweet, the out comedian amped up her disapproval of the president-elect, questioning his mental health and urging action to prevent his inauguration on January 20.

The post also linked to a CNN article, in which writer Harry Hurt III, who wrote a biography critical of Trump, said he was expelled from a golf course owned by the Republican politician.

In a series of tweets, O'Donnell also called Trump the "worst human," a "sick man," and a "criminal."

The comments are the latest event in a long-running feud between O'Donnell and Trump. The Republican politician made disparaging remarks against O'Donnell throughout his presidential campaign.

"I said very tough things to her and I think everybody would agree that she deserves it and nobody feels sorry for her," he said during a presidential debate with Democratic nominee Hillary Clinton. O'Donnell hinted in October she may be preparing for a defamation lawsuit in response to his vitriol.

Their fued has taken strange turns in recent months. In November, O'Donnell came out about her 3-year-old daughter's autism diagnosis in response to criticism of a recent tweet she posted speculating about whether Barron Trump, the youngest son of the president-elect, is autistic.