From the Associated Press:

In talking up a joint ticket, the Clintons may be seeking the upper hand, attempting to put her in consideration for the top of the ticket when she so far has failed to win the votes necessary to assure that she would face Republican presidential candidate John McCain in the November election.

The maneuver may also be aimed at countering an image in voters’ minds of Obama as presidential material and at helping restore an aura of inevitability as the party’s nominee that Clinton had early in the campaign but lost.

“The Clintons are in a difficult position,” said Dennis Goldford, a political science professor at Drake University in Iowa, who has tracked the presidential race.

“If she wins the Democratic presidential nomination, she would need Obama’s supporters. But she needs to be careful. If this talk of him on the ticket is seen as a cynical maneuver, it could backfire and hurt her,” Goldford said.