Not so sure about Santorum, he was inexperienced in dealing with MSM and was trapped too often in side issues such as contraception.
Newt on the other hand is experienced, shrewd, skilled orator. He would be far more effective president for change in the right direction.
With Romney, as presumptive nominee, he must be pushed, forced and pressured into the conservative direction. His tendency is to lurch to the center. However he is pliable and can be pushed to the right.