More than 100 Conservative MPs back an amendment to the Queen’s speech calling for an EU referendum bill.
Some 130 MPs, 115 of them Conservatives, voted for the amendment, with 277 opposed.
Although the prime minister was said to be “profoundly relaxed” about the vote, he was pushed into publishing a draft referendum bill on Tuesday to appease his backbenchers.
This bill is designed to show Tory backbenchers that Mr Cameron is serious about honouring his pledge in January to hold an in/out referendum on Britain’s membership of the EU if he wins the 2015 election.
But without a Conservative overall majority in the Commons, the bill has little chance of becoming law.
Mr Cameron, who was not present for the vote because he has been visiting the US, hoped the bill would win over Tory MPs likely to support the amendment.
But tonight’s vote shows there is still unease about the government’s approach.
He faced further problems when one of his MPs, Nadine Dorries, said she would talk to her local party about the possibility of standing at the next election as a joint Conservative/Ukip candidate. Downing Street said this was against party rules.
Tory MP John Baron, who proposed the amendment, urged MPs to back it on the basis that it would make it more likely a referendum bill made it on to the statute book.
Fellow Euro-sceptic Bernard Jenkin told MPs that people who voted Ukip in the local elections “will not be impressed unless we are making every effort to have a referendum as soon as possible, rather than when it suiits the three main parties …”
Labour opposed the amendment, but a small number of the party’s MPs were expected to vote for it.
Shadow chancellor Ed Balls told the Commons his party was not in favour of an in/out referendum now, saying the amendment “aims to break our ties with our main trading partner, blight inward investment into the UK and put at risk up to three million jobs”.
Chancellor George Osborne defended the government’s plans to seek a renegotiation of Britain’s membership of the EU and put the results to the voters in a referendum by the end of 2017.
He said people were now asking if membership benefited the economy, adding that if the prime minister could achieve “real change”, he would answer yes.
The Conservatives were forced to publish a bill in draft form because their Liberal Democrat coalition parties are refusing to allow it to be debated in the Commons in the way a government bill would be.
Ministers have suggested it could be adopted by a Tory backbencher as a private member’s bill.
Tory backbenchers were given a free vote on the referendum amendment, which is non-binding, but Conservative ministers were told to abstain.
Voted for referendum amendment to Queen’s Speech as I want people of #Bury to have their say on EU
— David Nuttall MP (@DavidNuttallMP) May 15, 2013
Sources close to the Tory leader insist that you mustn't call the 7.15pm vote this evening - on the amendment regretting the lack of a referendum bill - a "rebellion". Which begs the question as to why so many Tory whips are busily trying to turn some supporters into abstentions. Read Gary Gibbon's blog.