Democrats expanded their majority in the House with historic gains by dominating the Northeast and ousting Republicans in every region.

Their defeat of 22-year veteran Rep. Chris Shays in Connecticut gave Democrats every House seat from New England. Their victory in an open seat on New York’s Staten Island gave them control of all of New York City’s delegation in Washington for the first time in 35 years.

Democrats also rode the coattails of a decisive victory by Barack Obama in New Mexico to win one House seat they haven’t controlled in four decades and another the GOP had held for 28 years. Both were left up-for-grabs by GOP retirements.

“The American people have called for a new direction. They have called for change in America,” said House Speaker Nancy Pelosi, D-Calif. Exit polls showed voters troubled by the battered economy and deeply dissatisfied with President Bush.

Democrats unseated 12 Republican incumbents and captured nine open GOP seats, capitalizing on the unusually high 29 Republican departures. Republicans were only able to knock off four Democratic incumbents.

With fewer than a dozen races undecided, Democrats had won 251 and were leading for another five. Republicans had won 171 and were leading in six. If those trends held, Democrats could have a net gain of 20 seats. And Republicans were on track for their smallest numbers since 1994, the year a Republican Revolution retook the House for the first time in 40 years.

The Democratic edge in the current Congress is 235-199 with one vacancy in a formerly Democratic seat. Two Louisiana seats, one Democratic and one Republican, won’t be decided until December because hurricanes postponed their primaries until Tuesday.

It was the first time in more than 75 years that Democrats were on track for big House gains in back-to-back elections. They picked up 30 seats in 2006.

“This will be a wave upon a wave,” Pelosi said.

Republicans were licking their wounds and cheered themselves mostly by the prospect that Democrats — now holding the White House and bigger House and Senate margins — might overreach and position the GOP for gains in 2010.

“We sort of got through this, we think, a little bit better than some people might have expected,” said Rep. Tom Cole of Oklahoma, the head of the Republican House campaign committee. “Our worst days are behind us.”

Still, in the first hint of what promises to be a GOP shakeup, Rep. Adam Putnam of Florida, the No. 3 Republican, told colleagues in a letter released near midnight that he was “reluctantly” stepping down from his post.

In the northeast, GOP Reps. John R. “Randy” Kuhl of New York and Phil English of Pennsylvania were defeated. Democrat Eric Massa unseated Kuhl in New York’s southern tier, and Kathy Dahlkemper, a 50-year-old mother of five, toppled English in a swing district of rural communities and old industrial steel towns in Pennsylvania’s northwest corner.

In Connecticut, Democrat Jim Himes, a Greenwich businessman, defeated Shays despite the Republican’s highly publicized late criticism of McCain’s presidential campaign.

In upstate New York, former congressional staffer Dan Maffei won election to succeed retiring GOP Rep. Jim Walsh, becoming first Democrat in nearly 30 years to represent the district around Syracuse. Downstate, Democratic city councilman Mike McMahon won the race on Staten Island to succeed GOP Rep. Vito Fossella, R-N.Y., who was forced to resign amid drunk driving charges and revelations that he fathered a child from an extramarital affair.

In the South, too, Democrats made inroads. Montgomery Mayor Bobby Bright won election to succeed a retiring Republican in Alabama, despite his GOP’s opponents attempts to tie him to Obama. High school civics teacher Larry Kissell won in North Carolina, defeating Republican Rep. Robin Hayes.

Democrat Gerald Connolly, a former chairman of the Fairfax County Board of Supervisors, was elected to succeed retiring GOP Rep. Thomas M. Davis III in a northern Virginia district that’s trending more Democratic because of an influx of new voters. And in a heavily military district around Hampton Roads, Rep. Thelma Drake, R-Va., fell to Democrat Glenn Nye, who had been a foreign service officer in Aghanistan and Iraq.

In Florida, GOP Rep. Tom Feeney — under fire for ties to disgraced lobbyist Jack Abramoff — was the first incumbent to fall, losing to former state Rep. Suzanne Kosmas. To the east, Rep. Ric Keller, R-Fla., lost to Democratic attorney Alan Grayson, in an increasingly Hispanic district in Orlando.

Democrats also made inroads in the West, where Democratic businesswoman Betsy Markey in Colorado unseated conservative GOP Rep. Marilyn Musgrave. In the Las Vegas suburbs, veteran state legislator Dina Titus unseated Republican Rep. Jon Porter. In addition to the two open New Mexico seats, Democrats captured one in Arizona, left open by retiring GOP Rep. Rick Renzi, who’s awaiting trial on corruption charges.

In suburban Detroit, Democrat Gary Peters, a former state lottery commissioner and senator, ousted Republican Rep. Joe Knollenberg. In a Republican-leaning district in southern Michigan, Democrat Mark Schauer, a state senator, beat first-term GOP Rep. Tim Walberg. The Illinois Senate majority leader, Democrat Debbie Halvorson, won a seat formerly held by retiring GOP Rep. Jerry Weller in the swing exurbs and rural areas south of Chicago.

Democrats also knocked out 14-year veteran GOP Rep. Steve Chabot of Ohio in a district that includes portions of Cincinnati, which has the largest black population of any congressional district in the nation held by a Republican. Obama’s candidacy was a major factor in the race, where state Sen. Steven Driehaus won election. And Democratic state Sen. John Boccieri, an Iraq and Afghanistan veteran, captured the seat of retiring Rep. Ralph Regula, R-Ohio.

The news wasn’t all good for Democrats, who lost three first-termers in the South, and Kansas Rep. Nancy Boyda, whose Topeka-based seat went to Lynn Jenkins, the GOP state treasurer.

Republican attorney Tom Rooney defeated Rep. Tim Mahoney of Florida, who had admitted to two extramarital affairs just weeks before Election Day. Republican Bill Cassidy dealt a bruising defeat to Rep. Don Cazayoux, D-La., elected in a special election six months ago. And in Texas, Republican Pete Olson, a former chief of staff to Sen. John Cornyn, beat Democratic Rep. Nick Lampson.

But other freshman Democrats once considered vulnerable cruised to easy re-election.

First-term Democratic Reps. John Yarmuth of Kentucky, Indiana’s Joe Donnelly and Brad Ellsworth, and New Hampshire’s Rep. Carol Shea-Porter won easy re-election. They were part of a crop of freshman Democrats in conservative-leaning districts who began compiling campaign war chests and moderate voting records almost from the moment they were elected two years ago, leaving only a few of them endangered on Tuesday.

Former five-term Republican Rep. Anne Northup was unable to mount a comeback in Louisville, Ky., against Yarmuth despite GOP presidential nominee John McCain’s decisive victory in the state.

Rep. John P. Murtha, D-Pa., who chairs a subcommittee with the most influence on the Pentagon’s spending, who had a scare after calling his district south of Pittsburgh “racist,” won easy re-election.

Democratic candidates raised $436 million, compared with Republicans’ $328 million, according to federal data compiled by the nonpartisan Center for Responsive Politics. The Democratic Congressional Campaign Committee poured $76 million into competitive races and the National Republican Congressional Committee spent $24 million.

In Louisiana, indicted Democratic Rep. William Jefferson was cruising to victory in a Democratic primary.