Jeb Bush quickly grew testy on Wednesday during a town hall meeting in Summerville, S.C., as several of his supporters challenged his performance alongside front-runner Donald Trump on the campaign trail.

One questioner said he was an ardent supporter of Bush, but thought Trump had knocked Bush off message. Bush responded by saying the press is "at the mercy of Donald Trump," and noted that the billionaire blamed the 9/11 terrorist attacks on his brother former President George W. Bush.

"This is Michael Moore stuff. This is MoveOn.org stuff. No regular liberal would ever say that, only the radical Left people would ever say that," Bush said. "I will not take a step back for a guy that's like he is. Never."

A second questioner told Bush that Trump had indeed knocked him off message, at which point Bush interrupted.

"This is what I do. This is called campaigning right now," Bush exclaimed while glaring at a voter.

A third questioner questioner asked if the former governor would be willing to be a "son-of-a-b****" in the White House like his brother.

"Would I be an S-O-B?" Bush replied. "I will be tough. I will be resolute. I will be clear. I will be determined. ... If we're going to determine strength by craziness, we're going to have the weakest commander in chief."

The former governor then abruptly ended his town hall, after previously citing his desire to leave quickly to pick up an endorsement from a newspaper that he did not identify.

Bush, who ranks fifth out of six GOP presidential candidates in the Washington Examiner's power rankings, has campaigned with his brother in recent days. While the former governor appeared reluctant to display his toughness, his campaign sought to showcase his macho-side by releasing a video on Wednesday that features Bush chest-bumping his brother, the former president.