NPR Senior Washington Editor Ron Elving looks at some of the top vice presidential prospects on the Republican side.
John McCain has had more time than his rival to think about potential running mates, since he clinched the GOP nomination three months ago. McCain knows it's an important decision — even if he sometimes downplays it.
"The vice president really only has two duties. One is to cast a tiebreaking vote in the Senate, and the other is to inquire daily as to the health of the president," he has said.
McCain's own health is good. But because he'll be 72 on Election Day, his choice of an understudy does carry some extra weight.
Like Democratic presumptive nominee Barack Obama, McCain has tried to keep his selection process quiet. But that has only fueled speculation. Three weeks ago, when McCain hosted a barbecue at his country home in Arizona, political junkies scanned the guest list for possible running mates, despite McCain's protests that it was a social event, not an audition.
Three barbecue-goers drew special attention: former Massachusetts Gov. Mitt Romney, Florida Gov. Charlie Crist and Louisiana Gov. Bobby Jindal.
Minnesota Gov. Tim Pawlenty and former Rep. Rob Portman of Ohio also are considered candidates. Or, McCain could tap someone from outside government altogether, like former Hewlett-Packard Chief Executive Carly Fiorina.
McCain is getting questions and advice about his choice of running mate everywhere he goes — even the White House Rose Garden.
Kelly O'Donnell of NBC asked President Bush recently: "Sir, how would you counsel Sen. McCain to choose a running mate?"
Bush replied, "I tell him to be careful about who he names to be head of the selection committee."
Dick Cheney ran President Bush's selection committee — and ended up selecting himself.