One of Nick Clegg's worst moments in his debates with Nigel Farage came when he was asked what the EU would look like in 10 years' time. His response - "I suspect it’ll be quite similar to what it is now" - may have been honest but as Lib Dem strategists later acknowledged, it made him appear hopelessly wedded to an unsatisfactory status quo.
With this in mind, Clegg's speech tomorrow on EU immigration is his most significant attempt to date to demonstrate that he "gets" the need for reform. While defending the principle of freedom of movement, he will argue that migrants from new member states should not be allowed to move to other EU countries by registering as self-employed while transitional controls are in place.
He will say:
When Romania and Bulgaria joined, Labour said no one from those countries would arrive ahead of the transition controls being lifted at the beginning of this year.
Yet 60,000 Romanians and Bulgarians were already working here through a loophole for anyone who registered as self-employed.
Is it any wonder – when people have been repeatedly told one thing only to then see another - that so many have lost faith in government’s ability to manage the flow of migrants from new EU states?
Clegg will promise that the Lib Dems will "argue for the removal of the special exemption for the self-employed" and will "insist on it" if they are in government after the next election. "This loophole can’t be forced on Britain and we mustn’t accept it."
He will also propose allowing EU countries to "put the brakes on" immigration from new member states "if people begin arriving in numbers too big for our society to absorb successfully". This would mean giving Britain and others the right to extend transitional controls beyond the current maximum of seven years.
It is worth reflecting how significantly the Lib Dems' stance has changed since the 2010 election, when they argued for a (now abandoned) policy of "earned citizenship" for illegal immigrants. Their repositioning means that all three of the main parties now support tougher controls on future EU migration.
The danger for the Lib Dems is that their new policy will alienate those liberals who welcomed their unashamedly pro-immigration policy, but as the party's MPs will tell you, plenty of their voters, most notably in the south west, are far from relaxed about an open borders approach.