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"A bloody line has been crossed that cannot be ignored. At long last, Donald Trump has left the Republican Party few options but to act decisively and get this political train wreck off the tracks before something terrible happens," Scarborough wrote in The Washington Post.
The "Morning Joe" anchor has appeared increasingly unnerved by Trump's refusal to tone down his occasionally authoritarian rhetoric. But it seemed that his Monday suggestion about gun owners stopping Hillary Clinton from appointing federal judges was the tipping point.
"At this point, what else could Trump do that would be worse than implying the positive impact of a political assassination?" he asked.
Scarborough acknowledged the GOP was in "uncharted waters," but contended "that does not mean the way forward is not clear." He said it was time for the GOP to "start examining quickly their options for removing the Republican nominee."
During his Wednesday morning broadcast, Scarborough continued to make his argument, again saying that the real-estate magnate crossed the line into endorsing pseudo-fascist ideologies by potentially advocating for violence against Clinton.
"He crossed a lot of Rubicons yesterday," Scarborough said.
For his part, Trump soured on Scarborough months ago as the MSNBC host became increasingly critical of the Republican nominee, particularly over about his skepticism of the ability of a Mexican-American judge to properly oversee a lawsuit against him.
Nobody is watching @Morning_Joe anymore. Gone off the deep end - bad ratings. You won't believe what I am watching now!
- Donald J. Trump (@realDonaldTrump) June 8, 2016
Scarborough and Trump's relationship hasn't always been fraught.
Earlier this year, the MSNBC host faced criticism for allegedly going too easy on Trump during interviews, calling pundits who failed to recognize Trump's success "jackasses."