There are 33 Senate races this year, with Democrats defending 18 seats and Republicans defending 15. All 435 U.S. House seats are up for election. Democrats need to pick up 15 seats to take control of the House.
Congressional Balance of Power
Recent Election History
Republicans have controlled both chambers since 1994, except during a brief period when the Democrats held the Senate.
Washington Post analysis and candidate profiles for the most important races of Campaign 2006:
SOURCE: Staff reports | GRAPHIC: The Washington Post - Originally published February 06, 2006; Updated Oct. 5, 2006