PHOENIX -- Richard Carmona says he won't be running for Arizona governor in 2014, a decision that takes a likely front-runner out of contention for the Democratic nomination.
His party's nominee in last year's U.S. Senate race, Carmona said earlier this year that he was considering a run for governor.
However, Carmona told television station KPNX on Sunday that he decided the time isn't right.
Carmona, a former U.S. surgeon general, said the separation from friends and family during a campaign is a factor, along with time away from work.
``I'm still recovering. . It was a great experience, but it's just too soon,'' he said.
Carmona lost a tight Senate race to Republican Jeff Flake and was considered strongly positioned for the Democratic nomination for governor.
``If Rich Carmona had jumped into the governor's race, he would have gone all the way,'' said Chris Herstam, a former Republican legislator and longtime political observer. ``Now, because he's not running, it's wide open.''
Fred DuVal, a former Arizona Board of Regents president and a former Democratic National Committee member for Arizona, is actively exploring a candidacy.
His campaign-in-waiting has started announcing endorsements of DuVal from legislators and others in an apparent effort to show widespread support among party activists.
Another possible Democratic candidate is House Minority Leader Chad Campbell, a Phoenix Democrat who has signaled interest.
Campbell is the target of a recall campaign recently launched by Republican and tea party activists, and Campbell supporters on Monday filed papers for an anti-recall campaign committee for him.
On the Republican side, former Tempe Mayor Hugh Hallman has entered the 2014 governor's race, while other possible candidates include Secretary of State Ken Bennett, state Treasurer Doug Ducey and Mesa Mayor Scott Smith.
Gov. Jan Brewer has hinted she may run again, but the Arizona Constitution's term limits bar governors and certain other officeholders from serving more than two entire or partial consecutive terms.
Brewer, a Republican, was a midterm replacement for governor when Democrat Janet Napolitano quit to join President Barack Obama's Cabinet in January 2009. Brewer won a full term of her own in 2010.