He's a smart man. Best to wait another 4 years to take on the Governors seat (I believe Schwietzer is term limited), or take on Tester.
I think Rehberg will run for Governor. I'm not sure that he could wait that long to take on Tester.
Like BRTD said, they will be up at the same time. He might want to run for Governor, but he will be HEAVILY recruited by the Republicans to try and capture that other seat. The only way he won't run against Tester, and will run for Governor is if by 2012, Test has HUGE approval ratings.
