"We always recognized this was going to be a very challenging year," Republican National Committee Chairman Ken Mehlman said last night on CNN.

The first incumbent to go was six-term Rep. John N. Hostettler (R-Ind.), whose low-key, almost blase campaign style could not keep up with the polished candidacy of Vanderburgh County Sheriff Brad Ellsworth. He proved to be the first of three Indiana Republicans to lose. Rep. Anne M. Northup (R-Ky.), a proven survivor of Democratic assaults, then fell to Democrat John Yarmuth, a lightly regarded founder of an alternative newspaper.

From there, the Republican losses mounted quickly: both Republican seats in New Hampshire, House Appropriations subcommittee Chairman Charles H. Taylor in North Carolina and senior House Armed Services Committee member Curt Weldon in Pennsylvania. Rep. J.D. Hayworth (R-Ariz.), who made his name as a bombastic conservative and, more recently, a firebrand against illegal immigrants, lost to mild-mannered Harry Mitchell, the former mayor of Tempe.

"They voted their hopes, not their fears. We have gone to America with this positive agenda for change, with a better agenda for all our people," said House Minority Whip Steny H. Hoyer (D-Md.), who plans to seek the post of majority leader.

Taylor, of North Carolina, lost to former Redskins quarterback Heath Shuler, one of several Democrats in Republican districts who ran as moderate pragmatists, often sharing their constituents' more conservative stances on social issues, while vowing to put aside partisanship to produce the education, health-care and energy legislation that voters say they want. Republicans tried to attack these candidates as closet cheerleaders for the liberal Democratic leadership, but the tactic ultimately failed.

Republicans were still hoping to pick up two Democratic seats in Georgia, but late returns showed Democratic Reps. John Barrow and Jim Marshall narrowly leading in their races. That would set up another historic milestone: No party in modern times has failed to gain at least one seat in a House election, and Republicans were facing a shutout late last night.

Republicans faced the largest possible losses in the industrial Midwest and Northeast. In another early victory, Democrats took Vermont's only House seat, which was being vacated by Rep. Bernard Sanders, a liberal independent heading for the Senate. Republicans had hoped Martha Rainville, a well-polished adjutant general of the state National Guard, could blunt the Democratic surge by taking one seat from the Democratic column.

Charlie Cook, a nonpartisan political analyst, has called New York the potential GOP Waterloo. As many as half a dozen Upstate New York seats were in play, and expected landslide wins for Democratic gubernatorial candidate Eliot L. Spitzer and Sen. Hillary Rodham Clinton (D) might have depressed GOP turnout.

In Pennsylvania, three Republican-held seats were gone by midnight and two others were in danger. One of the Republicans' few bright spots was in Ohio, where losses were being held to a minimum. In New Hampshire, Republican incumbent Reps. Charles Bass and Jeb Bradley had appeared to be coasting to reelection, but both lost last night. Most of the Northeastern lawmakers who were in trouble are moderate or mainstream Republicans who try to steer clear of divisive and partisan battles. But they are highly vulnerable this year because of their support for the war in Iraq.

New Englanders in particular are deeply opposed to the war and furious at the Republican-led Congress for failing to challenge Bush's handling of it. Rep. Christopher Shays of Connecticut, long-serving and widely respected, eked out a victory, despite his unwillingness to call for the troop withdrawal that his constituents increasingly support.

After their successes in the East, Democrats quickly scooped up seats in the West, winning the seats of retiring Rep. Jim Kolbe (R-Ariz.) and Hayworth. The Democrats were also running strong races in conservative Kansas and Wyoming.

The size of the Democratic victory was yet to be determined. Democrats were favored to pick up seats in Colorado and Iowa, where two Republicans are retiring to seek governorships. In New Mexico, Rep. Heather A. Wilson (R), a perennial Democratic target, was facing the toughest challenge of her political career from state Attorney General Patricia Madrid. Other candidates, such as Reps. Jim Ryun (R-Kan.) and Barbara Cubin (R-Wyo.), faced strong challenges that few political observers predicted a year ago.

Three West Coast races promised to keep politics watchers up into the early morning hours. California GOP Reps. Richard W. Pombo and John T. Doolittle had been hammered for their associations with disgraced lobbyist and convicted felon Jack Abramoff and could lose despite the strong Republican registration advantage in their districts. Freshman Rep. David G. Reichert (R-Wash.) was challenged by Microsoft executive Darcy Burner, but a wild card in that race was a torrential rainstorm that caused serious flooding around the state, possibly depressing turnout.

The late surge that Republicans were trumpeting over the weekend fizzled on Election Day, as exit polls indicated strong preferences for Democratic candidates throughout the country. The National Republican Congressional Committee chairman, Rep. Thomas M. Reynolds (R-N.Y.), had said for months that Republicans could overcome a sour mood by keeping House races focused on local issues. A final advertising blitz by Republicans also sought to paint Democrats as too inexperienced to be trusted with control of the House.

But in exit polls, voters said their votes were determined by national issues, especially corruption and the war in Iraq. That was ominous for Republicans.