This morning on ABC's This Week, Sen. John McCain, R-Ariz., weighed in on Mitt Romney's hotly anticipated vice presidential pick.  The former presidential candidate's advice was clear.

"The absolute, most important aspect is, if something happened to him, would that person be well qualified to take that place?" said McCain.  "I happen to believe that was the primary factor in my decision in 2008.  And I know it will be Mitt's."

McCain picked Sarah Palin as his presidential running mate in 2008 and the decision has been much-discussed ever since.  Just this year, actors Ed Harris and Julianne Moore played McCain and Palin in the HBO adaptation of the book "Game Change."

McCain has dismissed these portrayals of his campaign as inaccurate in the past.

"I remember it well," McCain said this morning, laughing.

Washington is abuzz with speculation about who Romney will choose as a running mate.

While the vetting process is still very secretive, perceived frontrunners for the job include Sen. Marco Rubio, R-Fla.,  Sen. Rob Portman, R-Ohio, and Indiana Gov. Mitch Daniels among others.

McCain encouraged Romney to pick a person that "he knows he could trust."

"I'm very happy to say, we've got a very deep bench," McCain said.