A little-known Republican businessman from Queens, channeling voter discontent with President Obama into an upset, won election to Congress on Tuesday from the heavily Democratic district in New York City last represented by Anthony D. Weiner.
The Republican, Bob Turner, a retired cable television executive, defeated Assemblyman David I. Weprin, the scion of a prominent Democratic family in Queens, in a nationally watched special election.
With 84 percent of the precincts counted early Wednesday, Mr. Turner was leading Mr. Weprin by 54 percent to 46 percent, according to The Associated Press.
National Republican leaders immediately trumpeted the victory as a sign of trouble for Mr. Obama’s re-election effort. “An unpopular President Obama is now a liability for Democrats nationwide,” Representative Pete Sessions of Texas, the chairman of the National Republican Congressional Committee, said in a statement.
But Representative Debbie Wasserman Schultz of Florida, the chairwoman of the Democratic National Committee, said the district’s large concentration of Orthodox Jews made it unusual and meant the race had few national ramifications.
“In this district, there is a large number of people who went to the polls tonight who didn’t support the president to begin with and don’t support Democrats — and it’s nothing more than that,” she said in a telephone interview.
As Mr. Turner declared that the election had been a referendum on the president, his buoyant supporters, gathered at a restaurant in Howard Beach, Queens, shouted “Yes, we can,” appropriating the galvanizing phrase of Mr. Obama’s 2008 campaign. Mr. Turner predicted that voters elsewhere would also rebuke Mr. Obama in the elections next year.
“We have lit one candle today,” he said. “It’s going to be a bonfire pretty soon.”
Mr. Weprin, however, did not concede defeat.
“This is not over yet; this is going to be a long night,” he said in brief comments to his supporters at a pub in Forest Hills, Queens. “Hopefully we can still pull this out.”
The unexpectedly tight race stirred anxiety among Democrats already worried about elections next year for president, the House and the Senate. The Turner campaign had eagerly courted disenchanted Democrats, and outside polling places around the district on Tuesday, multiple longtime Democrats confessed that despite concern about Mr. Turner’s eagerness to slash federal spending, they chose him hoping that his election would get lawmakers’ attention.
“I am a registered Democrat, I have always been a registered Democrat, I come from a family of Democrats — and I hate to say this, I voted Republican,” said Linda Goldberg, 61, after casting her ballot in Queens. “I need to send a message to the president that he’s not doing a very good job. Our economy is horrible. People are scared.”
Mr. Turner will become the first Republican since 1920 elected to represent the Ninth Congressional District, which now stretches from the Rockaways to Forest Hills and encompasses a swath of middle-class and working-class neighborhoods in Brooklyn and Queens. The district is predominantly white and has long been known for its large Jewish population, though it has become increasingly diverse in recent years.
Mr. Weprin, 55, a former city councilman and son of an Assembly speaker, was nominated by local party leaders to run after Mr. Weiner, a Democrat, resigned in June following his admission that he had sent sexually explicit messages to women he had met online.
Mr. Turner, 70, ran against Mr. Weiner in the last election but has never held office. He mounted a surprisingly forceful campaign, painting Mr. Weprin as a party insider who would support the status quo.
Mr. Turner capitalized on discontent in some corners of the Jewish community with Mr. Obama’s posture toward Israel and his handling of the Middle East peace process. Former Mayor Edward I. Koch, a Democrat, urged voters to rebuke the president by voting for Mr. Turner.
The emergence of Israel as an issue was a surprise, because Mr. Weprin is an observant Jew and strong supporter of Israel. But Mr. Weprin’s support in the Orthodox community had already been weakened by his vote to legalize same-sex marriage, and several voters interviewed on Tuesday said the Israel issue was a major factor in their decision to support Mr. Turner, who is Roman Catholic. Mr. Turner repeatedly criticized Mr. Obama on Israel.
Mr. Weprin fought back by seeking to appeal to the district’s many older voters, telling them that Mr. Turner was in sync with the Tea Party and would seek to weaken Social Security and Medicare.
Erik Huneke, 35, a history Ph.D. candidate who voted for Mr. Weprin, said that setting aside discussion of national symbolism, there was no question that Mr. Weprin’s platform better suited the political leanings of most voters in the district.
“It’s understandable for people to be upset,” Mr. Huneke said. “But it would be nice if people had a longer-term perspective in terms of why they’re hurting now. It’s not just Obama’s fault.”
Mr. Weprin’s campaign made a central issue out of the future of federal entitlement programs, persuading voters like John Doherty, 64, a Democrat from Middle Village, Queens, to worry about whether Mr. Turner would favor deep cuts.
But Mr. Doherty, a retired social worker, said his concern about entitlement programs had been overshadowed by the opportunity he saw to express his unhappiness about the economy in the special election.
“We need to deliver a message to Washington,” he said. “We need jobs, and we need to focus on the economy, and we need to stop fighting with one another.”
The campaign was short — Mr. Weprin and Mr. Turner were chosen as nominees by their respective parties in early July — and attracted little attention or money for many weeks. As it became clear, however, that Mr. Turner might win, Mr. Weprin received a cash infusion from national Democrats, who spent more than $600,000 on television advertisements criticizing Mr. Turner. Mr. Weprin had also raised significantly more money than Mr. Turner and had the assistance of labor unions and strong local party organizations.
Both campaigns enlisted senior party figures to bolster their candidates. Mr. Turner trumpeted endorsements not only from Mr. Koch, but also from former Mayor Rudolph W. Giuliani and former Gov. George E. Pataki. Both made appearances with Mr. Turner and urged New Yorkers to vote for him as a way to admonish the president, for whom they did not have kind words.
On the Democratic side, Gov. Andrew M. Cuomo and former President Bill Clinton recorded automated phone calls to voters for Mr. Weprin, and Senator Charles E. Schumer of New York, who formerly represented the Ninth District, campaigned with him, as did the City Council speaker, Christine C. Quinn.
The upset in New York came the same day that, in a special election in Nevada’s Second District, an open seat was won by Mark Amodei, a Republican, over Kate Marshall, a Democrat. While Mr. Amodei’s victory was hardly a surprise, as the district has been held by a Republican since it was created in the 1980s, his defeat in the more Democratic leaning parts of the district demonstrated the challenge Democrats face in a country frustrated with high levels of joblessness and no near end in sight to economic woes.
The New York loss is an embarrassment to Representative Steve Israel, the chairman of the Democratic Congressional Campaign Committee. Mr. Israel just a few months ago had expressed hope that the Democrats could move to take back control of the House; now his party appears to be facing a challenge defending seats it already holds.
Colin Moynihan, Jim Rutenberg, Jennifer Steinhauer and Tim Stelloh contributed reporting.