Sullivan was considering a possible run after Gov. Tim Pawlenty announced last week that he won't seek a third term.
But Sullivan said he decided against it because he has young childrens and he's trying to start a new business.
"When I thought about what would be required to run for governor and what I would have to do with my business, it just didn't square," he said. "And I concluded the timing wasn't right for me."
Sullivan said he's not going to back any candidates at this point and added that he may run for another office in the future.
He ran in 2002 but narrowly lost the GOP endorsement to Pawlenty.
There are about two dozen Democrats and Republicans who are either running or say they're interested in running for the open seat in 2010.