Mitt Romney says Trump "has not risen to the mantle of the office."

[robkelk]

Romney - and every other candidate - has a delicate tightrope to balance on. Right now, he has to appeal to the 34% of Americans who will vote Republican even if the party nominated a stuffed bear. If he gets the nomination, he has to appeal to the ~33% who can be persuaded to vote according to their own interests instead of toeing a party line. (The other ~33% will vote Democrat even if the party nominated a stuffed bear.)

It's that swing group that he's appealing to with his comments. If he waited until after getting the nomination to try doing that, he'd appear to be an opportunist; making the comments now makes him appear to be a man of principle.