Two possible Obama VP picks coy on their prospects

WEST LAFAYETTE, Indiana (Reuters) - Two men often mentioned as possible running mates to U.S. presidential candidate Barack Obama joined him on the campaign trail in Indiana on Wednesday, further stoking speculation about the Democrat's closely guarded search for a No. 2.

Former Georgia Sen. Sam Nunn and Indiana Sen. Evan Bayh appeared flattered that their names were being bandied about in the media as vice presidential contenders.

But neither would comment on whether they had been contacted by the Obama campaign about the job.

"It's an honor, but I have no expectations of being offered any office. I am not in any way sitting on the edge of a chair, waiting to go back into government," Nunn told reporters.

"Certainly I would to talk to Sen. Obama if he wanted to talk about it," he added. "But I think the chances of an offer are pretty slim and I would have to do a lot of thinking ... about what was really the best role for me."

Bayh said he was enjoying his current job as a senator and added, "I think any questions about the vice presidential thing are understandable and it's good for my ego but I should probably let Sen. Obama and his campaign address those kinds of questions."

Nunn and Bayh are both respected voices on national security issues. Obama, a 46-year-old first-term Illinois senator, is trying to counter criticism from John McCain, his Republican rival in the November election, that he lacks the foreign policy seasoning to serve as commander-in-chief.

The two Democrats were part of a panel discussion with Obama at Purdue University in West Lafayette, Indiana, on the threats posed by nuclear and biological weapons and potential cyber attacks.

Obama said President George W. Bush's preoccupation with Iraq meant those issues had been neglected for the past eight years.

"It's time to break out of Washington's conventional thinking that has failed to keep pace with unconventional threats," he said.

The Democratic presidential candidate said if elected he would make eliminating nuclear weapons a central part of his security strategy.

"It's time to send a clear message to the world: America seeks a world with no nuclear weapons," he said.

Obama plans visits soon to Iraq and Afghanistan as well as Jordan, Israel, Britain, Germany and France. Dates for the trips have not been disclosed for security reasons.

Many analysts say it would make sense for Obama to pick a running mate steeped in national security experience to add heft to his ticket.

Nunn, 69, former chairman of the Senate Armed Services Committee, and Bayh, 52, and a member of the Senate Armed Services and Intelligence committees, both vouched for Obama's national security credentials.

"He has a history of thinking beyond the horizon, anticipating the kind of challenges we face," said Bayh, who campaigned for Obama's former rival, Democratic Sen. Hillary Clinton, during their race for the party's nomination but has since thrown his support to Obama.

(Editing by David Alexander and David Wiessler)