A Conservative MP says almost 100 colleagues have signed a letter calling on David Cameron to prepare legislation committing the UK to an EU referendum after the next election.
John Baron's letter does not specify an in-or-out referendum.
The wording would be decided later but "should relate to the nature of our... relationship with the EU", he said.
He says the law would "address the lack of public trust" which meant promises to hold such a vote "hold little sway".
Current laws commit the government to hold a referendum if Britain is asked to cede powers to Brussels.
In his letter Mr Baron says he believes "there is a consistent majority in this country who believe that the European Union meddles too much in our everyday lives".
It adds that "no-one in this country under the age of 55 has had the opportunity to express their view on this signally important matter".
It comes amid reports Foreign Secretary William Hague wants to launch a comprehensive audit of the impact of European Union law on Britain.
The coalition agreement includes a commitment to examine "the balance of the EU's existing competences" and, according to the Financial Times, Mr Hague wants to press ahead with such a study this summer.
Civil servants are expected to analyse the impact of EU law, without making recommendations on what powers should be repatriated from Brussels, according to the newspaper, with more details to be announced soon.
Many Conservative MPs believe Britain should go further renegotiate the terms of its EU membership and take back significant powers.
More than 100 of them earlier this year demanded that Britain should withdraw from the European Arrest Warrant and 130 other crime and policing rules.
Conservatives have also long pressed for Britain to be exempted from the European Working Time Directive and other laws they see as harming Britain's economic competitiveness.
Deputy Prime Minister Nick Clegg and fellow Lib Dem coalition members are likely to resist moves to repatriate powers.
Prime Minster David Cameron is, meanwhile, in Brussels for two days of talks with EU leaders about the future of the eurozone.
Mr Cameron insisted eurozone members were right to press ahead with closer fiscal integration but said Britain had different priorities.
"We want Europe to work for us, as a single market, as a place where we trade, as a place where we co-operate, and I'm going in there so that we get the safeguards to make sure that can keep happening."