LONDON — British Prime Minister David Cameron faced a humiliating rebellion by Conservative lawmakers after a vote on withdrawing from the European Union split his party.
Just days ahead of emergency talks on a European debt-crisis plan, Mr. Cameron last week ordered Conservative members of Parliament to oppose a motion calling for a referendum on EU membership.
The House of Commons was forced to debate the motion after a petition on the issue garnered 100,000 signatures, triggering an automatic parliamentary vote.
Mr. Cameron said Britain's membership in the EU was "vital for millions of jobs and millions of families." However, 81 Conservatives defied Mr. Cameron's orders, making it the largest rebellion on Europe since World War II.
Adam Holloway, a lawmaker who resigned from his position as personal private secretary to Europe Minister David Lidington, voted in favor of the motion, saying it is what his constituents want.
"I want decisions to be made more closely by the people affected, by local communities, not upwards toward Brussels," he said, referring to the Belgian capital that houses most EU operations.
Despite the rebellion, the EU referendum motion was rejected overwhelmingly by a majority of 372.
Ahead of the vote, Mr. Cameron made a strong appeal to members of his party who are disenchanted with the EU. In an attempt to head off a rebellion, he agreed that there is a need for "fundamental reform" of the EU, but he said a referendum on the issue was not the way to achieve this.
"There is a danger that by raising the prospect of a referendum including an in-out option, we miss the real opportunity to further our national interest," he said.
With an opinion poll showing overwhelming support for a referendum, some Conservative lawmakers said Mr. Cameron will face further rebellions unless he takes a tough stance in EU treaty negotiations in the next year.
Conservative Mark Pritchard said membership of the EU would become "more, rather than less, of an issue" during Mr. Cameron's next four years in office. He called for "greater clarity" on the government's plans to bring back powers to Britain that had been conceded to Brussels.
"If we don't have that clarity, I think the government's position on Europe is politically unsustainable, given the crisis in the eurozone and indeed possibly a game-changer just coming months down the line in Europe," he told BBC Radio.
"The Conservative Party will move on from the vote last night, but I do not think Europe, as an issue, is going to move on from this Parliament. It is going to be more, rather than less, of an issue."
The Liberal Democrats, coalition partners in the Conservative government, and the opposition Labor Party also instructed its members to oppose the motion. Labor leader Ed Miliband said the prospect of a referendum would create further "economic uncertainty."
"It is not the right thing for Britain," he said. "It is not the right thing for jobs. It is not the right thing for growth."
Emma Reynolds, the Labor member responsible for European affairs, said, "When unemployment is reaching a 17-year high, inflation is rising and the cost of living is going up, now is not the time to be debating whether to cut off our ties to our largest export market.
"The only real way to reform the EU is to be at the center, working with others to make it better, rather than shouting from the sidelines."
The vote also exposed differences on EU membership within the Labor ranks. Nineteen Labor members, including euro critic Gisela Stuart, defied Mr. Miliband's order.
"Apart from defense and a single currency, every aspect of British life has a dimension which has its roots in Brussels," she said.
"No one under 50 has been asked whether that is what they want. So it's about time the people are given their voice. If politicians don't trust the people, why should the people trust their politicians?"
Graham Stringer, a Labor member who voted for the motion, told BBC Radio, "I think it is a mistake of all three party leaders when the public are clearly aching for a say on Europe to say, no, you can't have it."
Britain's relationship with the EU always has been uneasy. Many Britons feel that Brussels has too much power over domestic affairs.
In the most recent opinion poll, carried out for the Guardian newspaper this week, 70 percent of voters want a referendum on British membership in the EU. The survey also found that 49 percent would vote to leave the EU, while 41 percent would vote to remain.
This is not the first time Europe has been a problem for a Conservative leader.
John Major, prime minister from 1990 to 1997, was brought down by euro critics in his party who opposed greater concentration of powers in Brussels.
Disagreements over Europe also eventually helped defeat Margaret Thatcher, prime minister from 1979 to 1990, who rejected proposals that would convert the European Economic Community into the European Union. She was ousted by pro-Europeans in her party.
For Mr. Cameron, the issue is arising as he is comes under pressure over the resignation of his defense secretary, Liam Fox. Mr. Fox quit after revelations that he had allowed a friend to access sensitive information and to attend meetings where government business was discussed.
The prime minister is also in trouble with female voters.
Polls show a decline in support among women after economic austerity measures hit women harder than men.
Many also are questioning his attitude toward women after he made comments perceived as patronizing and sexist in Parliament.
During a House of Commons debate, the prime minister told a female Labor member to "calm down, dear." In another debate, he told one of his fellow Conservatives that she was "clearly frustrated," a comment perceived by many as sexual innuendo.
Those gaffes followed controversy in the summer over revelations about the prime minister's relationship with senior executives at News International, the British arm of Rupert Murdoch's News Corp.
Soon afterward, street riots erupted in British cities, and Mr. Cameron was criticized for not returning from his vacation early enough to deal with the crisis.