Marco Rubio vouches for Mitt Romney's conservative credentials on Fox News.
"I've known Mitt Romney since 2007 when he first ran for president, I have had conversations with him throughout this process.
.... Here's what I would say to people that are concerned about him. Number one, this primary has been an excellent primary because it's made the candidates take very strong positions on issues that we can hold them accountable to.
I have zero doubt in my mind of two things. Number one, that Mitt Romney will govern as a conservative, and number two, that he will be head-and-shoulders better than the guy who's in the White House right now."
Obviously, if he's VP or a prominent surrogate, we'll hear much more detail about his positive take on Romney's record, but in this appearance on Hannity, he seemed to focus more on unity and the need to get Obama out than on Romney's record.
Nevertheless, without getting into specifics, "zero doubt" is a very strong endorsement of Mitt's cred.