AUSTIN - When a columnist reported this week that John McCain might announce his running mate in the midst of Barack Obama's international tour, it caused a stir.

Few episodes are guaranteed to generate more attention in the political theater of a presidential race. And for Mr. McCain, his decision on the ticket could tell a lot about how he hopes to win.

Conventional wisdom says that Mr. McCain, who at 72 would be the oldest president at inauguration if elected, needs somebody younger to boost the ticket's energy factor.

But there's more to the political calculus of picking a VP: Does he need a moderate to help lure independents?

Or a woman to woo disaffected Hillary Rodham Clinton supporters? Or a movement conservative to motivate the base, especially Christian conservatives who are lukewarm about Mr. McCain?

Or does the running mate really matter?

"Normally, these choices really have at most a marginal impact on the outcome of the election," said James Riddlesperger, a political science professor at Texas Christian University.

"But as close as presidential races have been, this could be significant," he said. "So they are not inconsequential."

Politically, a running mate can help counter an opponent's strengths and help compensate for the candidate's weaknesses.

In Mr. McCain's case, the Arizona senator has plenty of experience on the national stage and a personal narrative as a prisoner of war in Vietnam that provides an edge on foreign policy and military matters.

His problems with the evangelical base, his marginal credentials on the economy and his age are areas Team McCain would like to fix with the right running mate.

Fred Solop, a political scientist at Northern Arizona University, said Mr. McCain's choice doesn't have to be half his age but must project a vigorous persona and serve as a suitable stand-in as commander in chief.

"Someone who people could look at and feel confident they could take over the presidency if anything happened to McCain," he said.

First-term Louisiana Gov. Bobby Jindal, at 37, has the youth but lacks experience on the national stage - and has been busy this week tamping down speculation that he might be on the ticket.

Former Massachusetts Gov. Mitt Romney is only 10 years McCain's junior but, dark haired and ramrod straight, has the energetic looks to reassure voters, said Dr. Solop.

Moreover, Mr. Romney's business experience would be a plus with voters increasingly worried about the nation's economic woes.

On paper, the ideal addition to the McCain ticket would be a woman with appeal to Mrs. Clinton's supporters, conservative, a governor, comfortable with evangelicals and ready to occupy the Oval Office.

"You're never going to get somebody who fits all those criteria," said Dr. Solop.

Alaska Gov. Sarah Palin - a former high school basketball star, beauty queen and mother of five - is a rising GOP star whose selection would generate buzz for a party struggling to compete with Mr. Obama's rock-star status.

A more conventional female choice might be Sen. Kay Bailey Hutchison of Texas.

"I think Kay Bailey would be a wonderful running mate - but for the fact that she's from George Bush's home state," said Dr. Riddlesperger, noting the president's low standing in the polls.

Ultimately, there's the campaign arithmetic to consider - 270 electoral votes needed to win the White House. A candidate who can bring a swing state - like Gov. Tim Pawlenty of Minnesota or Gov. Charlie Crist of Florida - is worth his weight in hanging chads.

And the announcement itself is guaranteed to move the media spotlight your way. Word is the McCain camp could act soon, between wall-to-wall coverage of Mr. Obama's trip overseas and the opening of the Olympic Games in China next month.

The Dallas Morning News, July 26, 2008