E-mail this story to a friend Have comments? Send them to the editor. Printer Friendly Version Subscribe for Free!

WASHINGTON (AP) -- When Barack Obama shows up Saturday in Springfield, Ill., on his way to the Democratic Convention, he'll have his new running mate grinning beside him. But that man or woman is still unknown, even as speculation rises to a fever pitch.

Same with John McCain, just days away from his Republican convention.

A big reason the jobs are still open: The contenders believed to be still in the running could pose significant risks as well as helping the presidential candidates.

For Obama, for instance, picking a senator like Delaware's Joe Biden or Indiana's Evan Bayh would bring experience to the ticket but would also make it harder to emphasize his own signature campaign theme of change.

For McCain, former rival Mitt Romney would bring economic experience and ties to battleground Michigan. But Romney has his detractors, even among Republicans, and McCain's primary-season attacks on him would provide ammunition for Democrats.

For all the talk, running mates seldom are a factor in November outcomes. A party's No. 2 hasn't played a truly key role since John F. Kennedy chose Lyndon Johnson in 1960.

But the selection is the most important decision each candidate makes before formally gaining his party's nomination, and it could reveal much about his judgment.

"It's an opportunity for them to show that they know how to do it," said Paul Light, a professor of government at New York University. "In this regard, a bad choice hurts much more than a good choice helps."

Obama is believed to have narrowed his list to Biden, Bayh, Kansas Gov. Kathleen Sebelius and Virginia Gov. Tim Kaine. New York Sen. Hillary Rodham Clinton is still seen by some Democrats as a possibility -- but a longshot one.

Republican McCain, with an additional week or so to decide, is believed to have a short list that includes Romney and Minnesota Gov. Tim Pawlenty. Possibly also in contention: former Pennsylvania Gov. Tom Ridge and Connecticut Sen. Joe Lieberman, the Democratic vice presidential pick in 2000 who now is an independent.

Here is a look at the potential strengths and liabilities of the prospective running mates.

First, the Democrats:

- Biden, as chairman of the Senate Foreign Relations Committee, would bring a wealth of foreign policy experience, something the first-term Illinois senator clearly lacks. Just this past weekend he was in Georgia at the request of President Mikhail Saakashvili.

He's been in the Senate since 1972, a full ten years before McCain was first elected to Congress.

But the fact that Obama would turn to Biden in an effort to offset his own foreign-policy inexperience could be seen as a lack of confidence in himself.

Also, Biden, 65, has a spotty political history. He fared poorly as a presidential contender in this year's Democratic contests. He has a reputation for verbosity. And he is still dogged by his decision to drop out of the 1988 presidential campaign after he was caught lifting lines from a speech by a British Labor Party leader. Earlier this year, he apologized for describing Obama as "articulate" and "clean."

>> Continued -- Page 1 2 3

Copyright 2008 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.