Supporters of a bill to legislate for an "in-out" EU referendum in 2017 are continuing their efforts to get it on the statute book in the House of Lords.
A bill to enshrine an EU referendum in law has been killed off in the House of Lords.
A bill authorising a referendum was approved by MPs earlier this month.
Peers have voted to end the committee stage of the legislation, meaning it has run out of time to get through.
But there are doubts whether the private members bill will make it through the Lords before the end of the current session in April to become law.
The Tory MP behind the bill, James Wharton, blamed Labour and Lib Dem parliamentarians for killing it off for party political reasons.
The bill is not backed by Labour or the Lib Dems, who are expected to use blocking tactics to frustrate it.
Prime Minister David Cameron has said his pledge for a referendum in 2017 would stand even if the bill fails.
Independent crossbench peers and a few Conservatives are also expected to try and delay its progress.
Mr Wharton's private members bill was seen by Tory backbenchers as a way of strengthening the prime minister's commitment to an in-out vote.
The private members bill was launched by Tory MP James Wharton as a way of strengthening David Cameron's commitment to holding an in-out referendum.
BBC Parliamentary Correspondent Mark D'Arcy said he would not be surprised if the Conservatives made a fresh attempt to get the legislation on to the statute books next year.
'Respect'
The prime minister has repeatedly insisted he is committed to a referendum if the Conservatives win the the next general election.
Speaking at a joint press conference with French President Francois Hollande, Mr Cameron said "whether the bill succeeds or fails" it made "no difference to the pledge I am making on this in-out referendum".
The French president said he had "respect" for the choice to hold a referendum.
Asked whether David Cameron was ready to consider providing more time for the Bill in the Commons to give it a better chance of completing its passage through Parliament, the PM's official spokesman said: "Let's wait for the outcome of the current stage of the parliamentary process that is going on in the Lords.
"The prime minister wants it and would urge all parliamentarians to support the Bill.
"The House of Lords today has the opportunity to express its strong support for the British people having its say, and he hopes it will do so.
"Any parliamentarians that aren't taking that approach will have to explain their decisions."
'Penguins'
But Labour peer Lord Anderson of Swansea, who opposes the bill, said Mr Cameron's gamble in promising an in-out referendum would not pay off because Eurosceptic Conservative MPs would always want more.
"And they will ask for more rather like the penguins in the penguin house, they will swallow it down and demand more," said the peer.
"The trouble is that this government may be inclined to give it to them."
He accused Mr Cameron of being in "office but not in power" and losing authority and influence with the UK's EU "allies".
He accused the prime minister of "insulting" Mr Hollande "by saying in effect that the French economy, which is probably true, is substantially worse than our own, but it's not a way of influencing people and making friends."
The EU bill is on the second day of its committee stage in the Lords, but could be pushed into a third day.
So far there has been little sign of the filibustering tactics seen at previous stages of the bill's passage through Parliament, with peers steadily working their way through 15 groups of amendments.
Even if the committee stage concludes on Friday, there is normally a two-week gap before the report stage, meaning it would not return to the chamber until 14 February, when peers are on a half-term break.
But there may be an attempt to bring the report stage forward.
The next available sitting day is 28 February, which is also the last day set aside for the Commons to deal with private members' bills, leaving the bill some way from becoming law.
