I've Got The Scars To Prove It

John McCain often says, "I've stood against my party and I've got the scars to prove it!" What does he mean by this?

Near as I can tell, he's been affected very little by standing up to his party. Standing against other Republicans has raised his public profile and image in general. It also hasn't hurt him enough with Republicans because he's still their Presidential nominee!

It seems to me there's actually a clause missing in the middle of this statement where he means to say, "I've stood against my party, fought in a war, and I've got the scars to prove it."