Arizona Gov. Janet Napolitano is endorsing Barack Obama for the Democratic nomination for president, The Associated Press has learned.
Napolitano planned to make her intentions known during a conference call Friday, according to an individual familiar with her plans who spoke on condition of anonymity because she hadn't publicly discussed the decision.
The endorsement is a major gain for Obama in his race against chief rival Hillary Rodham Clinton. One of several female governors, Napolitano is in her second term.