[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2008/images/12/02/art.ap.bill.richardson.jpg caption=" New Mexico Governor Bill Richardson is headed to Washington."]
(CNN) - Bill Richardson and Janet Napolitano: Both are governors of neighboring states in the Southwest. Both are headed to Washington. But their departure is triggering very different succession scenarios in their home states.
CNN has learned that New Mexico Governor Richardson will be nominated tomorrow as President-elect Obama's Commerce Secretary. For Richardson, who was Energy Secretary and UN Ambassador under President Clinton and a former Congressman from New Mexico, it means a return to the nation's capitol.
But who takes Richardson's job?
That person would be the state's lieutenant governor, Democrat Diane Denish, who stands to become become New Mexico's first female governor. Denish was Richardson's running mate in the 2002 and 2006 elections and with the governor term-limited out of the 2010 race, was planning a gubernatorial run of her own.
While the governorship in New Mexico stays in Democratic hands, it's just the opposite in neighboring Arizona.
That state's governor, Janet Napolitano, was nominated yesterday by Obama to serve as Secretary of Homeland Security. Arizona doesn't have a lieutenant governor, so when Napolitano steps down to head to Washington, Arizona Secretary of State Jan Brewer — a conservative Republican - takes over the job.