Former GOP presidential nominee Sen. John McCain (Ariz.) had a piece of advice for current presumptive nominee Mitt Romney: Make sure you pick a vice president who can do the job.

McCain, who in 2008 perhaps made the most talked-about vice presidential pick in modern history with Sarah Palin, said today that the two most important qualities needed in a candidate to share the national ticket are trustworthiness and the ability to assume the responsibilities of president if the worst happens.

“I think it’s a person that he knows he can trust,” McCain said on ABC’s “This Week.” “The primary, absolute most important aspect is, if something happened to him, would that person be well-qualified to take [his] place. I happen to believe that was a primary factor in my decision in 2008, and I know it will be in Mitt’s, and I’m happy to say we’ve got a very deep bench.”

McCain was widely reported to have wanted friend and veteran lawmaker Sen. Joe Lieberman (I-Conn.) to be his No. 2, but his advisers pushed Palin, then the governor of Alaska, to try to boost the conservative credentials of, and excitement level around, the ticket.

Though the Romney campaign has been mum about which politicians are on its vice presidential short list, many political operatives have predicted it includes Sens. Rob Portman (Ohio) and Marco Rubio (Fla.), House Budget Chairman Paul Ryan (Wis.) and a handful of governors.