"I think of all the Republican candidates who are prominent, I think Romney would be the one I would rather see have a slight possibility to be president," on MSNBC's "Jansing & Co" in an interview that aired Wednesday.
When pressed on whether he would be "comfortable" with a Romney presidency, Carter responded, "I would rather have a Democrat, but I would be comfortable."
Carter accused Romney of going to the "extreme right wing" to win in the GOP primary, but said he believes candidates on both sides of the aisle tend to move toward the middle during the general election.
"I think he's gone too far in the conservative positions to suit the average American, that's why I think President Obama is going to be reelected," he said.
He also got in a dig against Romney, saying he has the perception of being "changeable" in his positions.
"I think that's a stigma that he's already been able to weather, at least in a Republican primary. If he moves back more to the central position on some major issues, I'm not sure that he can suffer anymore as being changeable," said Carter.
Romney may not only be Carter's top choice, but his only choice. The former Massachusetts governor moved closer to garnering his party's nomination with a five-state primary sweep Tuesday night.
Newt Gingrich's campaign confirmed to The Hill on Wednesday that the former House Speaker will formally exit the race next week. Rick Santorum dropped out of the GOP contest earlier in April, leaving Rep. Ron Paul (R-Tex.), who has an enthusiastic base of support, but failed to gain traction with Republican electorate.