Romney, seen as a likely candidate for president in 2012, said Thursday that his political action committee has written a check to Deal's campaign. Romney previously endorsed Karen Handel, who lost the Republican nomination to Deal in a runoff election last month.

Deal spokesman Brian Robinson said the campaign was grateful for Romney's support.

"He is a respected Republican leader and an expert on business issues. Those who know the most about getting Georgia's economy going again are expressing their faith and support in Nathan Deal," Robinson said.

Romney was in Atlanta on Thursday stumping for statewide GOP candidates including Sen. Johnny Isakson and Sam Olens, candidate for attorney general.

Isakson's campaign said a fundraiser headlined by Romney Thursday evening drew about 50 people and raised an estimated $50,000.

"I made a commitment to help in key races," Romney said when asked why he had come to Georgia to help the junior senator get elected to his second term, saying that Isakson is "doing better and better."

"I'm surprised at just how well he's done," Romney said.

When asked about his predictions for the November midterm elections, Romney stopped short of handicapping the races.

"I think you'll see us do well in the House as a repudiation of Obama-style liberalism," he said. "I can't tell you how many seats we're going to pick up."

Romney also said the tea party movement was good for American politics.

"Their energy and passion is good for my party and good for my country," he said.