In order from least plausible to most plausible among the five who fit all the criteria, here's the scouting report:
His resume is a wonder to behold. His competence is readily apparent to any voter.
McCain seems to have developed a personal dislike for him, and McCain is not good at hiding such sentiments.
Minnesota Gov. Tim Pawlenty:
Pawlenty seems able to keep conservatives happy while presenting a friendly persona.
Former House Budget Committee Chairman John Kasich:
There is no doubt that Kasich has an appealing and approachable personality
he can come across as a bit hyperactive, which might exacerbate rather than modulate McCain's intensity.
He immediately gives forth an air of (that overused word) gravitas, and he seems to be liked and respected by people across the entire ideological spectrum.
But is he a true Reaganite?
The best choice, bar none.
Other columnists have also written that he would make a good Veep choice