Fox News senior judicial analyst Andrew Napolitano Andrew Peter NapolitanoFox's Napolitano says grand jury erred in Taylor case: 'I would have indicted all three of them' Fox's Napolitano: Supreme Court confirmation hearings will be 'World War III of political battles' Fox's Napolitano: 2000 election will look like 'child's play' compared to 2020 legal battles MORE said Monday that President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE's "foul language" and "dog whistles of lawless behavior to many of his supporters" call into question "the president's fitness for office.”

"He publicly calls people crude names, uses foul language, and sends dog whistles of lawless behavior to many of his supporters," said Napoltano on "Liberty File" on Fox Nation, the network's streaming service that launched one year ago. "All of that is a question of free speech, personal taste and political risk."

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"But threats to ignore parts of the Constitution are not matters of speech, taste or risk," the former judge continued. "They reveal character traits but question the president’s fitness for office.”

Napolitano has emerged as one of Trump's "bluntest critics" on Fox News amid the impeachment inquiry over the president’s dealings with Ukraine, per an Associated Press profile published Monday.

In the same profile, Napolitano was asked if he would vote to impeach the president if he were a Democrat in the House.

“If I could modify your question to ask if there’s a legal basis to argue high crimes and misdemeanors, then the answer is yes,” Napolitano said. “That’s really beyond dispute ... If I were a Democrat in the House, which I am not and never will be, I would vote to impeach.”

The perspective comes as the political world braces for the first televised public hearings in the impeachment probe, set to begin on Wednesday.