I think Switch was a booster for him too. He may have changed his mind though.
Honestly, if Paul and Huckabee would drop out and support Romney, who has a much better chance then both of them and is pretty similar in his stance, McCain would have a 33% to 67% race against him. It wouldn’t even be a challenge anymore.
Not to mention, if Romney gets the nomination, he might have a chance to win the White House. If McCain gets the nomination, the Republicans will not see the White House for at least another 4 years (no, they won’t even be invited to debate on new laws, Democrats do not include Republicans, only Republicans desire to work with Democrats on legislation) because people, like me, will actively campaign for the Democrat instead of voting Republican.