Topeka ? Secretary of State Ron Thornburgh is seriously considering a run for governor in 2010.

The Republican said Monday that although he’s not ready to make an announcement, he is determining how much support he might have.

“This is a game in which timing is everything. The time feels right for us right now, in that we’ve got great support around the state of Kansas,” he said.

Gov. Kathleen Sebelius, a Democrat, won’t be able to seek re-election again because the state constitution limits her to two terms.

Thornburgh took a step in June toward seeking the GOP nomination by appointing a treasurer for a potential campaign. Under state law, a candidate can’t raise or spend any campaign funds without a treasurer.

He is the first potential candidate in any party to appoint a treasurer.

“Right now, I am testing the waters,” he told The Associated Press. “We are gauging the support that has been out there. I’ve had people talk to me for years about potentially doing this.”

Thornburgh, 44, began his state government career in the secretary of state’s office, eventually rising to the top assistant’s job.

In 1994, Republican Bill Graves gave up the secretary’s job to run for governor, and Thornburgh was elected to replace him. Thornburgh won re-election in 1998, 2002 and 2006.

Before seeking a fourth term last year, Thornburgh considered but decided against seeking the GOP nomination and the right to challenge Sebelius. He said he would have to sacrifice too much time with his sons, Greyson, now 10, and Tanner, now 7.

He said time away from family will be a crucial issue before he decides whether he’ll run for governor in 2010. But he added that he and his wife, Annette, are confident their sons can deal with an intense, statewide campaign.