US Republican Senator John McCain had some advice for his party's presumptive nominee to take on President Barack Obama: choose someone you trust for vice president.
McCain, who lost the election four years ago to Obama, a Democrat, picked Sarah Palin as his running mate. His choice of the little known Alaska governor with limited experience on the national stage fired up the Republican Party's conservative base, but failed to stem a Democratic tide.
McCain was asked on ABC television's "This Week" how he would advise former Massachusetts governor Mitt Romney about picking a running mate.
"I think it's a person that he knows he could trust, and the primary -- the absolute, most important aspect is, if something happened to him, would that person be well qualified to take that place?" McCain said.
"I happen to believe that was the primary factor in my decision in 2008. And I know it will be Mitt's."
Palin, who was savaged by critics for being divisive and unprepared, resigned as Alaska governor after losing the election and went on to become a media personality and a vitriolic critic of the Obama administration.
One of the names mentioned as a possible Romney running mate is Cuban-American Marco Rubio, a 40 year-old senator from Florida who is a favorite of "Tea Party" conservatives.
Rubio, speaking on "Fox News Sunday," said the economy was worse off under Obama, and dismissed the president as a divisive Washington politician.
"All of the things that made him different and special four years ago are gone, and now, all he does is run dividing Americans against each other, obviously, because he can't run on his record," said Rubio.
But he dodged questions about a possible vice presidential run with Romney.
"I'm not going to talk about the vice presidential process," Rubio said. "But I can tell you that there are multiple ways that someone can help our nominee and I look forward to doing that."
Vice President Joe Biden joked that he might be interested in running in 2016 paired on a ticket with Secretary of State Hillary Clinton.
"I think we may run as a team," Biden told NBC's "Meet The Press" when asked to discuss his political future.
"I'm only joking obviously," Biden quickly added. "I don't know. I don't know whether I'm going to run and Hillary doesn't know whether she's going to run."
Clinton, who ran a tight campaign against Obama in 2008 in a failed bid to win the Democratic nomination, has ruled out any further White House bids.
But Biden said he was entirely certain that he will be Obama's 2012 running mate, despite speculation the president would try to strengthen the ticket's appeal by choosing Clinton instead.
"There is no question about it. There's no way out. They've already printed Obama-Biden (campaign posters)" he said. "You are looking at the vice presidential candidate of the United States of America."