The news that immigration is unlikely to fall significantly in 2011 should set alarm bells ringing in Downing Street. An IPPR study  published today suggests that net migration will remain around the 200,000 mark, far short of the government's flagship promise to reduce net migration from "the hundreds of thousands to the tens of thousands".
The report cites several reasons why net migration will remain high: increased economic migration from the EU (which the government cannot legally restrict) as the UK economy continues to outperform those of Spain, Portugal and Greece; increased emigration from Ireland (120,000 Irish nationals are expected to leave the republic in 2010 and 2011); higher immigration from Latvia and Lithuania (the numbers have risen from 25,000 to 40,000 a year); and lower emigration from the UK (30,000 left in the year to March 2010 compared to 130,000 in the year to March 2008).
Along with the EU, immigration is one of the issues that the Tory right wants to see significant progress on before the end of this parliament. The imperative of deficit reduction means that dissent has so far been limited. Cameron has projected himself as a quasi-war leader, even channelling Lord Kitchener in his conference speech ("Your country needs you"). Conservatives, more than most, are susceptible to such rhetoric. But expect patience to wear thin as time goes on. The Tory right, like the Lib Dem left, will begin to demand greater concessions from the coalition.
One should add that the possibility of Conservative failure on immigration represents a big political opportunity for Ukip and the far right. There is always a danger at times of high unemployment that voters will turn to populists and demagogues in search of solutions. On Twitter, the Ukip leader, Nigel Farage , correctly points out: "Good report by IPPR on immigration, Cameron's cuts are meaningless. If euro collapses in 2011 expect a flood from Europe we can't control."
Cameron's decision to raise unrealistic expectations on immigration will return to haunt him.