WASHINGTON — Virtually unknown a month ago, Christine O’Donnell rode a surge of support from tea party activists to victory in Delaware’s Republican Senate primary Tuesday night, dealing yet another setback to the GOP establishment in a campaign season full of them. A second insurgent trailed in a long, late count for the GOP nomination in New Hampshire.

O’Donnell defeated nine-term Rep. Mike Castle, a fixture in Delaware politics for a generation and a political moderate. Republican Party officials, who had touted him as their only hope for winning the seat in the fall, made clear as the votes were being counted they would not provide O’Donnell funding in the general election campaign.

She enters the fall race as an underdog to Chris Coons, a county executive who was unopposed for the Democratic nomination. The Republican state chairman, Tom Ross, said recently she “could not be elected dogcatcher,” and records surfaced during the campaign showing that the IRS had once slapped a lien against her and her house had been headed for foreclosure. She also claimed falsely to have carried two of the state’s counties in a race against Vice President Joe Biden two years ago.

With unemployment high and President Barack Obama’s popularity below 50 percent, Republicans said a run of hotly contested primaries this spring and summer reflected voter enthusiasm that will serve the party well in the fall. The GOP needs to win 40 seats to take the House and 10 for control of the Senate.

Democrats counter that the presence of tea party-supported Republicans on the ballot on Nov. 2 would prove costly to the GOP. That proposition will be tested in seven weeks’ time in Senate races in Nevada, Colorado, Florida, Kentucky — all states where establishment Republican candidates fell in earlier primaries — and now Delaware.

In the other marquee race of the night, for New Hampshire’s Republican Senate nomination, former Attorney General Kelly Ayotte overcame an early deficit and moved ahead of Ovide Lamontagne as returns piled up after midnight. Her lead was slightly less than 1,000 votes with ballots counted from 83 percent of the state’s precincts. No final result was likely for hours, if not longer.

Ayotte was backed by establishment Republicans as well as former Alaska Gov. Sarah Palin. Lamontagne, a former chairman of the state Board of Education, campaigned with the support of tea party activists.

The winner will face Democratic Rep. Paul Hodes, who is giving up his seat in the House to run for the Senate.

Nearly complete returns from Delaware showed O’Donnell with 53 percent of the vote. “Don’t ever underestimate the power of ‘we the people,”‘ she told supporters who cheered her triumph.

But Coons issued a statement moments after Castle’s defeat. “We cannot let Joe Biden’s seat fall into ultraconservative hands,” he said.

In other races, Democratic Attorney General Andrew Cuomo of New York faced no opposition for the party’s nomination for governor, and he will be the prohibitive favorite in the fall for an office his father held for three terms.

Political novice Carl Paladino, a wealthy developer who enjoyed tea party support, defeated former Rep. Rick Lazio for the Republican nomination — an additional shock to the establishment. Lazio won the conservative party nomination and a spot on the November ballot anyway.

Wisconsin businessman Ron Johnson defeated two minor opponents for the Republican nomination to oppose three-term Democratic Sen. Russ Feingold in November in what polls show is a tight race. Johnson has said he will spend millions of his own money to finance his campaign through Election Day.

In New York, 40-year veteran Democratic Rep. Charles Rangel easily won renomination in his first time on the ballot since the House ethics committee accused him of 13 violations, most of them relating to his personal finances.

And Washington D.C. Mayor Adrian Fenty was booted from office by primary voters, despite spending weeks apologizing for what he conceded was arrogant behavior across four years in office. City Council member Vincent Gray outpolled Fenty and is virtually assured of victory in November.

In all, five states chose nominees for the Senate, and six more had gubernatorial hopefuls on the ballot in the final big night of a primary season marked by recession and political upheaval. The winners had scant time to refocus their energies for midterm elections on Nov. 2.

Castle’s defeat boosted the number of members of Congress who have lost primaries to eight, five Republicans and three Democrats. But that list does not include a lengthy list of GOP contenders who fell to tea party-supported challengers despite having the backing of party officials eager to maximize their gains in November.

In a postscript from one of them, Republican Sen. Lisa Murkowski of Alaska is expected to announce by week’s end whether she will mount a write-in campaign following her primary defeat last month.

The Republican primary in Delaware took a sharp turn for the negative three weeks ago after the Tea Party Express, Palin and Sen. Jim DeMint of South Carolina announced they would come to O’Donnell’s aid.

Castle, a former two-term governor and a veteran of nearly two decades in the House, was repeatedly assailed as a liberal, a Republican in name only. He and the party responded by challenging O’Donnell’s fitness for public office.

In an extraordinary move, the state Republican Party launched automated phone calls attacking O’Donnell in the campaign’s final hours. The calls feature the voice of a woman who identified herself as Kristin Murray, O’Donnell’s campaign manager in her 2008 unsuccessful Senate campaign, accusing the candidate of “living on campaign donations — using them for rent and personal expenses, while leaving her workers unpaid and piling up thousands in debt.”

Biden resigned the seat in early 2009, shortly after being sworn in as vice president, and his successor, Democratic Sen. Ted Kaufman, pledged not to run for a full term.
The GOP establishment confronted a possible second defeat in Delaware, where businesswoman Michelle Rollins trailed in a race for the nomination for the state’s lone House seat in late returns. John Carney was unopposed for the Democratic nomination.

In Maryland, former Republican Gov. Bob Ehrlich won the nomination for a rematch against the man who ousted him from office in 2006, Democratic Gov. Martin O’Malley.
In Wisconsin, Milwaukee County Executive Scott Walker defeated former Rep. Mark Neumann for the Republican nomination for governor. Milwaukee Mayor Tom Barrett won the Democratic nomination.

Rangel’s principal challenger for the nomination in his Harlem-based district was Adam Clayton Powell IV, a state assemblyman whose father Rangel defeated 40 years ago. In the decades since, Rangel rose to become chairman of the House Ways and Means Committee, with enormous power over taxes, trade, Medicare and more, but Democrats forced him to step aside from that panel while he battles ethics charges.

He is accused of accepting several New York City rent-stabilized apartments, and omitting information on his financial disclosure forms. He’s also accused of failing to pay taxes from a rental property in the Dominican Republic, and improperly soliciting money for a college center to be named after him. He has vowed to fight the charges, and faces an ethics committee trial, possibly after the elections.

A second New York Democratic incumbent, Rep. Carolyn Maloney, won easily despite a spirited challenge.

Rhode Island had a rare open seat in its two-member House delegation, following the decision of Democratic Rep. Patrick Kennedy to retire. Providence Mayor David Cicilline, who is openly gay, defeated three rivals for the Democratic nomination.