"You know that if I did know, I wouldn't tell you," said Bill. "But I honestly don't know."
David built a case for the former Secretary of State, citing recent polls that place Hillary as a frontrunner in the Democratic Party.
"We've created this climate in America where you're running all the time," complained Bill, who had a 13-month campaign when he ran in 1992.
As the election is still three years away, Bill says that there are more immediate issues (e.g. healthcare, food stamp assistance, etc.) that should be taken care of before Hillary decides whether to run.
Late Show with David Letterman airs weeknights at 11:35/10:35c on CBS.