CONWAY, S.C. - Another Mitt Romney event, another flub from Sen. John McCain, who today mixed up the names of GOP candidates when trying to cast differences between Romney and his counterparts.

"Lindsey Graham and Jim DeMint have joined with me time and time again to go to the floor of the senate to fight against the earmark, pork barrel corruption that goes on in Washington D.C., said McCain, speaking at a rally in a peanut warehouse. "Earmarks are a gateway to corruption. I can tell you that neither Mitt Romney nor Rick Santorum share that view."

What McCain had meant to say was that neither Newt Gingrich nor Rick Santorum share that view.

McCain quickly tried to recover, going on to hit Gingrich on the earmark spending.

"When Newt Gingrich was speaker of the house, earmarks exploded," said McCain. "Rick Santorum sponsored earmark after earmark. I went down to the floor and fought against those. My friends, earmarks are the gateway to corruption."

"Members of congress went to jail and I guarantee you this president," said McCain, pointing at Romney, "Will fight against it time after time."

During a rally on Thursday in Charleston, McCain erred when he replaced President Obama's name in a line that was meant to laud Romney.

"I am confident, with the backing of the American people, President Obama will turn this country around," said McCain, immediately catching his error. "President Romney."

McCain officially endorsed Romney on Wednesday, and has been campaigning with the former Massachusetts governor in New Hampshire and South Carolina since.

Addressing claims by the media that McCain and Romney aren't actually as friendly as they might want voters to think, McCain defended their relationship.

"Yes, we fought hard in the 2008 primaries, but I'd also like to remind you that as soon as that was over we got together, and nobody worked harder than, no one worked harder for my campaign, than one Gov. Mitt Romney and I'll always be grateful for that," said McCain.

McCain offered the crowd some of his famous "straight talk."

"I'd like to give you some straight talkin'," said McCain. "[Romney's] going to do well in New Hampshire, not as well as the polls it's going to close up some, but he's going to win in New Hampshire."

"It's going to come down my friends, as it always does, to South Carolina," he said. "We're not taking a single vote for granted."

"This could be a very, very close South Carolina election," he said. "If Mitt Romney wins here he will be the next President of the United States."

"South Carolina it's up to you, it's up to you."