The latest is Governor Janet Napolitano of Arizona:

Napolitano is the most prominent Democrat in Arizona and her endorsement could be significant in a state now regarded as winnable by a Democratic presidential candidate after decades as a near-lock for Republicans. The state holds its primary on Feb. 5.

Napolitano, 50, was elected governor in 2002 and re-elected in 2006. She previously was U.S. attorney for Arizona during most of the Clinton administration and then served a four-year term as the elected state attorney general.

She is regarded as a possible candidate in 2010 for the U.S. Senate seat now held by Republican John McCain, though she has been mentioned as a possible candidate for vice president or for a Cabinet post in a Democratic administration.

A pretty significant get. Whatever momentum Hillary Clinton might have coming out of New Hampshire, it is clear that she still has a major fight on her hands.