WASHINGTON — Republicans won enough crucial races Tuesday to retain control of the House of Representatives, beating back a strong Democratic challenge and allowing the GOP to keep pushing an agenda of fiscal austerity.

The GOP was on track to hold on to a strong majority in the chamber, according to early returns, ensuring that House Speaker John Boehner, Ohio, remains the dominant Republican legislator in negotiations over government spending in the months ahead.

The continued GOP dominance in the House probably will lead to renewed clashes with Senate Democrats, with whom Boehner's conservative caucus feuded for the past two years in budget battles that brought the federal government to the brink of defaulting on its debt.

Those partisan showdowns made the 112th Congress the least-popular in history. Although that seemed to bode ill for incumbents — several in both parties fell to primary challengers in the spring and summer — voters Tuesday followed an old axiom: They loathe Congress but support their local congressman.

Many incumbents survived because of a redistricting process that left a record-low number of competitive seats, cloistering Republicans and Democrats together into geographically odd — but politically homogenous — districts. In Florida, where population growth boosted the delegation to 27 seats, only six races were considered competitive entering Election Day.

Even the most outspoken partisan from Florida, freshman Rep. Allen West, R, held a slight lead over his challenger late Tuesday, due in part to his move north into a more Republican-leaning district where his controversial statements were considered less inflammatory. Conversely, Alan Grayson — a liberal firebrand tossed out in the 2010 wave — was set to return to the House from a new district that tilts heavily toward Democrats.

West led by fewer than 2,000 votes with nearly all precincts reporting. In Chicago's northwest suburbs, Iraq war veteran and former Obama administration official Tammy Duckworth knocked off Rep. Joe Walsh, an outspoken conservative who ran an aggressive campaign. By late Tuesday, Walsh was the only freshman Republican to have been defeated, although several more trailed. In Minnesota, Rep. Michele Bachmann, who founded the Tea Party Caucus months before the 2010 midterms, was locked in a fight for her political life, leading businessman Jim Graves by fewer than 2,000 votes with more than half the vote left to be counted.

Although Democrats, who needed a net gain of 25 seats to reclaim the majority, spent hundreds of millions of dollars attacking the "tea party Congress," early returns showed they were not making enough inroads in the eastern half of the nation to make up that ground. A veteran Democratic incumbent was knocked off in Kentucky, while touted challengers were in neck-and-neck races. Democrats remained hopeful that, once key targeted races in the West were tallied, they could produce an overall net gain of at least a handful of seats.

After casting his ballot in the southwestern Ohio district he has represented for 22 years, Boehner vowed to continue the conservative track that House Republicans have taken the past two years, arguing the results validated their approach.

"For two years, our majority in the House has been the primary line of defense for the American people against a government that spends too much, taxes too much, and borrows too much . . . The American people want solutions — and tonight, they've responded by renewing our majority," Boehner said in a victory address in Washington.

The Democratic defeat left in doubt the political future of House Minority Leader Nancy Pelosi, Calif., who for months had publicly and privately predicted huge gains for Democrats and a possible recapture of the chamber's majority. Pelosi allies have signaled that she may relinquish her leadership role if President Obama were reelected and Senate Democrats remained in charge.

House Democrats declared "the end of the tea party" before election returns began coming in Tuesday night. Their strategists pointed to the difficult reelection fights for several of the most outspoken conservatives in the House, including Bachmann, Walsh and West.

Democrats also noted that many others who rode in on tea party support two years ago tried to reposition themselves as mainstream Republicans to face this year's electorate.

"House Republican incumbents — and their candidates — are running as far away from the Tea Party as they can," the Democratic Congressional Campaign Committee declared in its memo.

The GOP performance defied early expectations that Republicans' historic 2010 gains would be followed by steep losses this November — the historical pattern after large wave elections such as the 63-seat gain for Republicans two years ago.

Experts have noted that the Republican strategy after 2010 was to use the decennial process of redistricting to fortify as many of the 87 freshmen as possible for the 2012 races. Rather than trying to seek large gains, Boehner's team worked with GOP-controlled state legislatures, which draw district maps, to shore up those freshmen in new districts.

Of the more than 80 Republican freshmen standing for reelection, more than half had been reelected by late Tuesday.

Both parties hoped to notch several historical firsts in the election. In the North Shore of Massachusetts, former state senator Richard Tisei was in a tight race against a veteran, scandal-plagued incumbent in his bid to become the first Republican to win as an openly gay candidate. With more than 50 percent of the vote counted, Rep. John Tierney, D, led Tisei by less than 4,000 votes. In Utah, Mia Love, the mayor of Saratoga Springs, was in a tossup race with Rep. Jim Matheson in her effort to become the first black Republican woman elected to Congress. In Hawaii, Democrat Tulsi Gabbard was the favorite to win an open seat and become the first Hindu-American in Congress.

Gabbard's expected victory is part of the continuing diversification of House Democrats that most believe will leave their caucus of close to 200 members with a majority of women and minorities. If that occurs, it will be the first time in history that a House or Senate party caucus does not have a white male majority.

Some candidates were expected to win despite their scandals. In Chicago, Rep. Jesse Jackson Jr., D-Ill., who ran a vigorous primary campaign in a newly drawn district that went deep into the suburbs beyond his South Side base, has not been seen in public since early June, when he entered a treatment facility for what his doctors said was bipolar disorder. He was expected to easily win reelection in his heavily Democratic district, but his aides have still not signaled when he will return to the Capitol.

In Staten Island, N.Y., freshman Rep. Michael Grimm, R, was favored to win reelection despite an active FBI investigation into his campaign finances from his 2010 race. In the last 10 days of the campaign, after Hurricane Sandy's destruction of his district, Grimm was a frequent presence on his district's streets and in media appearances pleading for help.

The redistricting process also created several incumbent-vs.-incumbent races, including a pivotal race in Cleveland's suburbs pitting freshman Rep. James Renacci, R, against Rep. Betty Sutton, D. That race was a potential harbinger of the presidential contest. Renacci, an entrepreneur who has owned several businesses, embodies the GOP business mantra embraced by Boehner and Romney. Sutton, a member of the moderate Blue Dog Coalition, represents her party's prior successful effort to appeal to exurban and rural voters with a mix of fiscal conservatism and socially liberal views.