MSNBC's Joe Scarborough repeatedly called Donald Trump "Amnesty Don" on Monday in response to the Republican presidential nominee's recent signals that he may not be interested in deporting all illegal immigrants.

"For 14 months, Amnesty Don has been putting illegal immigration at the center of Amnesty Don's campaign," Scarborough said on MSNBC. "And yet nobody in Amnesty Don's own campaign can tell you what Amnesty Don's position is."

The GOP nominee's initial hardline approach to immigration was an early centerpiece of his campaign, before he announced last week that he would be opening to "softening" his position.

"But now Amnesty Don is softening ... So now Amnesty Don this weekend, even Amnesty Don's own people, surrogates, don't know what Amnesty Don's going to do on this," Scarborough said. "Isn't it surprising that some people are calling him Amnesty Don?"

The hashtag "#AmnestyDon" began trending on Twitter shorty after the exchange, and became the number one topic one point during the morning.

The hosts of Morning Joe have been feuding for weeks now with Trump's campaign. Scarborough authored an opinion piece published in the Washington Post the evening before where he called out Trump for his "hateful personal attacks" against him and his cohost, Mika Brzezinski.

"These days, a rudely out-of-bounds Trump attack surprises Mika and me about as much as a puppy relieving himself on a living room rug. We've figured out by now that it does no good to lose your cool with the puppy or Donald Trump, since neither have any control over their bladder or mouth," he said, adding that the GOP has nominated "a reality TV showman" who "obsessively" talks about himself.

After former Democratic National Committee Chairman Howard Dean argued during the show that Trump is becoming increasingly "unattractive" to Republican working class voters, Scarborough seemed to agree. "They are starting to peel off and say, 'Do I really want to be voting for Amnesty Don?'" he asked.

On Monday's show, Scarbough joked that he should write a song called Amnesty Don that will form the basis of a country Western musical, with the Republican presidential candidate starring as a cowboy who bursts into the doors of a saloon with guns in his hands only to say, "Aw, hell, ya'll can go home now."