But in Tennessee, Republicans claimed one of the other premier races when former Chattanooga mayor Bob Corker (R) defeated Rep. Harold E. Ford Jr. in the election to succeed retiring Senate Majority Leader Bill Frist (R).

In one of the most-watched Senate races, Sen. Joseph I. Lieberman of Connecticut, who lost the Democratic primary to businessman Ned Lamont because of his support for the war and the president, turned the tables and easily won reelection.

In New York, Sen. Hillary Rodham Clinton (D) rolled up a big margin as she cruised to a reelection victory that is widely seen as a step toward a presidential campaign in 2008.

In New Jersey, appointed Sen. Robert Menendez (D) overcame a challenge from state Sen. Thomas H. Kean Jr., robbing Republicans of a seat that not long ago they thought they may be able to win. In Minnesota, a newcomer, Hennepin County Attorney Amy Klobuchar, held on to the seat of a retiring Democratic senator. In Maryland, Rep. Benjamin L. Cardin (D) was the winner over Lt. Gov. Michael S. Steele in the contest to succeed retiring Sen. Paul S. Sarbanes (D).

In Massachusetts, Sen. Edward M. Kennedy (D) won an eighth term. Democrats also held Senate seats in Delaware, Florida, Hawaii, Michigan, Nebraska, New Mexico, North Dakota, Washington, West Virginia and Wisconsin. In Vermont, Rep. Bernard Sanders (I) won the seat of retiring Independent Sen. James M. Jeffords.

Republicans held on to their Senate seats in Arizona, Indiana, Maine, Mississippi, Texas, Utah and Wyoming.

House results trickled in at first and then came in a torrent. Some of the most prominent Republicans were among the losers last night.

One was Rep. Nancy L. Johnson (Conn.), who won her first race in 1982 when Republicans were losing two dozen districts. She lost to state Sen. Chris Murphy. In Kentucky, Rep. Anne M. Northup has been targeted by Democrats in virtually every election but until last night was a survivor. She was defeated by John Yarmuth, editor of an alternative newspaper.

In Iowa, Rep. Jim Leach (R), who was not considered particularly vulnerable, lost to Dave Loebsack in a district that Sen. John F. Kerry won in the 2004 presidential election.

In Florida, Rep. E. Clay Shaw Jr., one of the most powerful Republicans in the House, lost his reelection bid to state Sen. Ron Klein. Republicans also lost the seat of former congressman Mark Foley (R), who resigned in disgrace over sexually explicit Internet messages sent to a former House page.

In Arizona, Rep. J.D. Hayworth, one of the GOP's most vocal and visible conservatives and a hard-liner on immigration, lost his reelection bid to former state senator Harry Mitchell. The Arizona Republic newspaper had endorsed Mitchell, referring to Hayworth as a "bully."

Republicans lost the scandal-scarred seats of former congressman Robert W. Ney in Ohio and former House majority leader Tom DeLay in Texas. Scandal also contributed to the defeat of two Pennsylvania incumbents, Rep. Curt Weldon (R), who lost to retired Navy Vice Adm. Joseph Sestak, and Rep. Don Sherwood (R), who fell to Christopher Carney.