The selection of a running mate is often, but not always, overrated. Consider the present . . . .

Ken Rudin, NPR Political Editor, Washington Desk, writes in Political Junkie:

The feeling four years ago was that John Kerry's naming of John Edwards was an inspired choice, but after all was said and done it's hard to see where he helped. No southern state, including Edwards' home of North Carolina, voted Democratic that year. And for all the fanfare of having Geraldine Ferraro on the Democratic ticket in 1984, Walter Mondale still lost 49 states.

But sometimes it really has mattered. Lyndon Johnson may have been the difference between victory and defeat for John Kennedy in 1960. Bill Clinton threw conventional wisdom out the window in 1992 when he picked fellow Southerner and baby boomer Al Gore, who turned out to be the most influential vice president in history. That is, until the next administration, when George W. Bush got the foreign policy gravitas he was lacking when he named Dick Cheney. No vice president in history has ever had the power that Cheney has had during the past seven-plus years.

For McCain, the choice of a running mate is important for two reasons. One, he needs to send a signal to doubting conservatives that he is really one of them. True, in what still appears on paper to be a Democratic year, he's got to win over independents and independent-minded Democrats if he is going to make it to 1600 Pennsylvania Ave. His campaign knows that there could very well be a resistance from some voters come November to vote for a woman or an African-American. But he can't name a moderate to the ticket either, and certainly not one who is pro-choice.

And two, there is the age factor. At 71, McCain would be the oldest person ever to win the presidency. His mother, Roberta, is 95 years old and shows no sign of slowing down. So for all we know, McCain could live forever. But he has had cancer. At the least, we may be looking at a one-term president. And so the person he picks as a running mate will be eagerly watched.

Here are some possibilities, some more possible than others, listed alphabetically. Subsequent Junkie columns will review their chances:

Mississippi Gov. Haley Barbour
Former Florida Gov. Jeb Bush
Florida Gov. Charlie Crist
Sen. Lindsey Graham of South Carolina
Former Arkansas Gov. Mike Huckabee
Sen. Kay Bailey Hutchison of Texas
Sen. Joe Lieberman (I-D) of Connecticut
Alaska Gov. Sarah Palin
Minnesota Gov. Tim Pawlenty
Former Rep. Rob Portman of Ohio
Former Massachusetts Gov. Mitt Romney
South Carolina Gov. Mark Sanford
Sen. John Thune of South Dakota