U.S. Rep. Todd Tiahrt, R-Goddard, will make an announcement at 11 a.m. Saturday at the Capitol Plaza Hotel in Topeka about his plans for 2010.Tiahrt is widely expected to announce his plans to seek the Senate seat by retiring Sen. Sam Brownback, who will seek the GOP nomination for governor. Tiahrt, who recently began his eighth term, already announced his Senate campaign steering committee, which includes state Reps. Lance Kinzer, Peggy Mast and Kasha Kelly, and former Kansas House Speaker Doug Mays.This would set up a GOP primary between Tiahrt and seven-term Rep. Jerry Moran, R-Hays, who announced his plans to run earlier this week.Moran’s camp has already released a poll that shows Moran running ahead of Tiahrt, 41 percent to 25 percent, in a potential matchup.Pundits have speculated that the survivor of Moran-Tiahrt could face Democratic Gov. Kathleen Sebelius in a Senate race. Term limits prevent Sebelius from seeking another term as governor.