I dunno the challenge could come from the left like Bernie Sanders to make Obama look like a centrist or a real challenge from the center like the governor of MT who has a track record:
Brian Schweitzer
Montana | Next Election: 2012
Summary
Governor Brian Schweitzer was elected governor in 2004 and re-elected in 2008. He served as Chair of the Democratic Governors Association in 2008. Montana voters re-elected Governor Schweitzer in 2008, when he defeated State Senator Roy Brown by 33 percent even while Republican Sen. John McCain carried Montana by 2 points in the same election.
Date of Birth: September 4, 1955
Percent of Vote Won in Previous Election: 65.4%
Accomplishments:
Creating more jobs at higher wages than anytime in history
Cutting more taxes for more Montanans than any other time in the state’s history, including a $400 rebate to Montana homeowners
Increasing Montana’s electrical generation capacity more during his administration than the previous 16 years combined. The state is one of only two states in the country to have increased oil production, raising it by 50 percent
Investing more in both K-12 and higher education than any previous administration – while also capping tuition at our state’s colleges and universities, the first such effort in a generation
Increasing the number of children on the Children’s Health Insurance Program by more than 3,000. The program now provides quality healthcare to more than 16,000 kids and gives them a healthy start in life
Upgrading Montana’s bond rating for the first time in 26 years with Moody’s, Fitch and Standard and Poor’s Investment Services – a sign of sound fiscal management in state government