Former Rep. Tom Campbell (R-Calif.) appears primed to switch from California's governor's race to its Senate race, and it looks like he will make an announcement Thursday morning.

In an invitation from the Los Angeles County GOP to an event featuring governor candidate Steve Poizner, Chairwoman Jane Barnett says Campbell won't be coming to the event "as a candidate for governor."

"Tom Campbell has notified me that he will not be visiting with us as a candidate for Governor this Thursday," Barnett writes. "He will be making an announcement that morning -- so stay tuned to the news."

Campbell apparently thinks he can make more of a dent in the Senate primary, where Carly Fiorina's personal funds aren't on the same level as Meg Whitman and Steve Poizner. They have each spent about $19 million of their own money; Fiorina has spent $2.5 million.

Campbell would join a primary that also features state Assemblyman Chuck DeVore, a favorite of the conservative grassroots and tea party crowd. DeVore's camp thinks he's closer as a candidate to Fiorina, and that his presence helps their campaign.

Campbell served two stints in Congress, from 1989 to 1993 and 1995 to 2001.