Dems Drop First Open Seat

South Dakota has provided the first party-switch in the House this evening. Republican John Thune has beaten Democrat Rick Weiland in the seat Democratic Rep. Tim Johnson left open when he went after Larry Pressler's Senate seat.

The first tossup race has been called: Republican Edward Whitfield of Kentucky's 1st district has held onto his seat after a strong challenge from Democrat Dennis Null.

The next big wave -- 12 states -- close up their polls at 9 p.m. ET: Arizona, Colorado, Louisiana, Minnesota, Nebraska, New Mexico, New York, North Dakota, Rhode Island, South Dakota, Wisconsin and Wyoming.