Former Republican presidential nominee John McCain on Sunday advised presumptive Republican nominee Mitt Romney to selected a running mate that "he knows he could trust."

"The absolute most important aspect is if something happened to [Romney], would that person be well qualified to take that place?" McCain told ABC's Jake Tapper on Sunday. "I happen to believe that was the primary factor on my decision in 2008. I know it will be Mitt's. I'm very happy to say we've got a very deep bench."

As for what was the "best advice" he could give Romney, McCain offered: "I think it's a person that he knows that he could trust."

According to the HBO movie Game Change, McCain worried that his vice presidential running mate, then-Alaska Gov. Sarah Palin, "might start turning on me" if he tried to stop her from "going rogue."

The Arizona senator joked last month that Romney's vice presidential nominee "should be Sarah Palin."

(h/t: ABC News)