In the battle for the U.S. Senate next year, Dems will have to defend 18 seats while Republicans will have to defend 15 seats.

Only one incumbent U.S. Senator faces a serious challenge for his party’s nomination. That’s Robert Bork’s favorite Republican Arlan Specter. Conservative Congressman Pat Toomey, 100% rating by the American Conservative Union, is challenging Specter, 50% American Conservative Union rating. Rachel DiCarlo writes in the latest ’Weekly Standard’ about that race. Specter has lined up party regulars including the White House and Rick Santorum but in a closed primary DiCarlo things Toomey has a chance. The best sign that this might be true is that Specter is already running ads attacking Toomey.

If re-elected Specter will be Chairman of the Senate Judiciary Committee. Orrin Hatch’s service as Judiciary Committee Chair will end because of Senate Rules limiting the terms of Committee Chairmen.