The Tory leadership was engaged in another push for radical action on the EU today, amid signs David Cameron's promise of a referendum may have encouraged rather than subdued eurosceptics.
As the deadline nears for lifting restrictions on Romanian and Bulgarian freedom of movement in the EU, a growing group of Tory MPs are demanding the government block the move, in a bid to stop another wave of immigration from eastern Europe.
Former ministerial aide Stewart Jackson told the Observer newspaper he would consider putting forward a bill in parliament if there was no movement from Downing Street.
"I am considering it but I want to find out what is happening with the ministerial group being led by immigration minister Mark Harper," he said.
"If they are going to bring forward proposals, then fine. If they are not then I would be strongly minded to come forward with a bill."
The enthusiasm for action on the free movement question suggests Nick Clegg was right in his strategic judgement that handing eurosceptics an EU referendum would fail to neutralise the threat from the right of the party.
Backbenchers cite the arrival of between one and two million eastern Europeans after Poland and seven other European countries were allowed to enter in 2004 as a sign of what could happen in December when controls end.
The government is not putting forward any predictions of numbers from Romania and Bulgaria and ministers have tried to play down the development.
"Estimates of these things have often been grossly wrong in the past," William Hague said.
"I don't think it will be a major issue."
Boris Johnson said the ending of the controls in December "unquestionably poses problems" for London, amid pressure on housing and school services.
"We need to think about this – especially considering the underestimate in the number of people who came from Poland and the other accession countries the last time," he said.
The influx of Poles in 2004 was partly a result of Britain's then-strong economy. The numbers coming this time around could be lower because of the economic situation in the UK.
There is also a greater choice of countries to move to for Bulgarians and Romanians than there were in 2004.