Trump rally attendee appears to mock president during his speech. Minutes later he’s replaced.

In what has become a trademark of his presidency, Donald Trump delivered yet another fiery speech heavy on immigration and Hillary Clinton at a political rally in Billings, Mont., Thursday night. The president also veered off topic several times, including one moment where he compared himself to Abraham Lincoln and claimed Civil War-era reporters refused to recognize the greatness of the Gettysburg Address.

"They had fake news then. They said it was a terrible, terrible speech," Trump said. "Fifty years after his death they said it may have been the greatest speech ever made in America. I have a feeling that's going to happen with us. In different ways, that's going to happen with us."

Despite Trump's heated rhetoric, it was a man standing behind the president during the rally who stole the show. As the president spoke, the rally attendee quickly went viral for his apparent inability to contain his colorful reactions to what Trump was saying.

During the middle of Trump's speech, the man can been seen briefly speaking to a woman who ends up taking his place in the crowd.

Minutes later, a woman wearing a "Make America Great Again" hat also standing behind the president was also replaced.

It's unclear if the two women were employees or volunteers of Trump's presidential campaign. Neither the White House nor Trump's 2020 presidential campaign immediately responded to a request for comment.

The man's identity wasn't immediately known, but according to Edward Nelson, a Democratic candidate for state representative, the man was wearing a Democratic Socialists sticker.

This isn't the first time the campaign has intervened to downplay apparent protests of Trump. During a rally in Evansville, Ind., last week, a volunteer member of Trump's advance team jumped in front of the camera of Associated Press photographer Evan Vucci as he was attempting to take a picture of a protester.

That volunteer was taken off the road by the campaign, according to the White House Correspondents' Association. Olivier Knox, the association's president, told the Washington Post that Trump's campaign said the actions were those of an "inexperienced volunteer" and that the campaign "promises that this will not happen again."

Trump was in Billings to campaign for Republican senate candidate Matt Rosendale, who is taking on Democratic incumbent Sen. Jon Tester in a highly watched race that could impact Democrats' chances of taking control of the Senate. Montana is one of just five states that Trump won by double-digits in 2016 where a Democratic senator is up for re-election.

According to the most recent poll of the race, conducted by WPA Intelligence for the National Republican Senatorial Committee in August, Rosendale led Tester by two points, within the margin of error.

The Cook Political report rates the seat "likely Democratic."