Last week, UK Prime Minister David Cameron said that any member of the Conservative Cabinet campaigning to quit the European Union, would have to leave the government. Later, he withdrew the statement.
The rebel lawmakers want to guarantee that the government will not make the referendum coincide with any other election.
Conservative Member of Parliament William Cash said, quoted by the newspaper on Sunday, that a plan on changes to referendum rules could succeed if they have the support of both the Labour and the Scottish National Party (SNP).
Tapping into a growing wave of euroscepticism and anti-migration sentiment in the country, UK Prime Minister David Cameron promised to let Britons vote by the end of 2017 on whether or not to leave the 28-member bloc in the event of his Conservative Party winning the May 7 general election.
Defying all predictions, the Tories won 331 of the House of Commons' 650 seats, securing a comfortable majority and handing Cameron his second term in office.
The prime minister has repeatedly said that Britain should stay in the European Union, but on renegotiated terms.