TOPEKA, Kan. (AP) — A national tea party group has endorsed U.S. Sen. Pat Roberts's re-election in Kansas after previously supporting his opponent in the Republican primary. The Tea Party Patriots Citizens Fund announced Tuesday it is supporting Roberts because it will be harder for Republicans to regain a Senate majority if he loses. It says it wants to block Democratic President Barack Obama. The 78-year-old Roberts is seeking his fourth six-year term, and is in a tight race with independent candidate and 45-year-old Olathe businessman Greg Orman. Orman is running as a centrist and says voters have a choice of continuing partisan gridlock or electing a problem-solver. The tea party group endorsed Roberts's challenger, Milton Wolf, in the August GOP primary and was active in Mississippi's contentious Republican primary.