More than two thirds of the public wants the coalition to claw back powers from Brussels, according to a poll.
And a majority would support refusing to sign any new European treaty unless that happens.
The research, carried out by Harris Interactive for the Daily Mail, comes after David Cameron suffered a huge rebellion by his own backbenchers over calls for a referendum on EU membership.
The Prime Minister is now under huge pressure to return powers to Westminster as part of the process for agreeing an expected new EU treaty.
However, he faces strong resistance from his Liberal Democrat deputy Nick Clegg who does not believe the balance with Brussels needs to be radically changed.
Whitehall officials are said to have been ordered to draw up an assessment of the "risks and opportunities" that could arise for Britain as a result of a new treaty.
Harris Interactive found that 49% of people were in favour of a referendum on EU membership, while 23% were against. Overall 68% of those interviewed believed powers needed to be returned to the UK, compared to 13% did not. Among Conservatives the margin widened to 88% and 7%.
Just under half thought negotiations should start now, but 32% said they should wait until after the eurozone crisis eases.
The most popular areas for repatriation of powers were immigration (86%), human rights law (71%) and employment law (65%).
Some 54% said Britain should not agree to a new EU treaty until progress is made.