Sen. John McCain said today that it was “foolishness, it’s stupid,” to dwell on his past criticisms of former Massachusetts governor Mitt Romney.

“We came together immediately after the campaign was over” in 2008, McCain told The Post after appearing with Romney in Charleston, S.C. He endorsed his 2008 rival Wednesday. “Thats a tradition we have. To make anything else out of it is foolishness, stupid.”

Romney, joined by McCain and South Carolina Gov. Nikki Haley, continued his “crony capitalism” attack against President Obama.

“I understand how the things the president’s doing kills jobs,” Romney said. “He’s a job killer. He doesn’t mean to be, he just is.” He accused the president of using his position to help his allies in organized labor, saying, “He wants to give jobs to those who give him the money.”

In her introduction, Haley highlighted Romney’s support for South Carolina in a now-resolved dispute with the National Labor Relations Board over a Boeing plant. The candidate released an ad on the subject this morning.

There were a few Romney-isms. He introduced his wife and McCain’s by saying, “There are two beautiful — well, at least two — there are many beautiful women in this audience.” Later, rhapsodizing about “America, the Beautiful,” he said of the song’s amber waves of grain, “When I was in Iowa I pretended that corn qualified. That may have gotten me those eight votes I needed so badly.”

McCain, meanwhile, congratulated Clemson University on winning a football game they actually lost 70 to 33, eliciting a loud groan from the crowd. He groaned himself when he briefly confused Romney with Obama.

But overall, the two appeared more comfortable with each other than they did during Wednesday’s endorsement announcement.

McCain was also quick to attack one of Romney’s rivals, criticizing former Pennsylvania senator Rick Santorum for supporting earmarks: “Senator Santorum and I have a strong disagreement. He thinks earmarks and pork barrel projects are good for America”

There were no disruptions from Occupy protesters, and a crowd of about 400 gathered for the rally at Charles Towne Landing state park.

After the event, Haley pointed to the audience as evidence that reports of anti-Romney sentiment in the state were overblown. Unlike McCain, she pledged to stay positive, telling reporters after the event, “I don’t need to bring anyone else down to make Gov. Romney look good.”