UK 25 April 2016 The Leave campaign will struggle to win by playing the immigration card For most voters, the economy trumps migration as the defining issue. Getty Images. Sign UpGet the New Statesman\'s Morning Call email. Sign-up If you're losing an argument, change the subject. After being thrashed last week on economic territory (by a grand coalition of George Osborne, Mark Carney and Barack Obama), the EU Leave campaign has followed this advice. In an article for his former parish, the Times, Michael Gove warned of an immigration "free-for-all" if the UK voted to remain, contending that five applicant states - Turkey, Albania, Serbia, Macedonia and Montenegro - pose a "direct and serious threat" to living standards and public services (though Britain could veto the entry of each). On the Today programme, his fellow Brexiter Iain Duncan Smith declared: "The reality is that we have to accept people, even criminals." You could call it "Project Fear". Britain's high immigration rate is undeniably of concern to many voters. The boast that EU withdrawal would exempt the UK from free movement (though Norway and Switzerland show it may not) is perhaps the best card the Brexiters have to play. But it may not deliver victory. The Remain campaign speaks of a "plateau" beyond which Leave cannot advance. There are millions of people whose priority is reducing immigration - just not enough for the outers to win. The issue is to them what the NHS was to Ed Miliband's Labour - a strategic comfort blanket. A recent ComRes poll found that the economy led migration by 47-23 per cent as the defining subject for the electorate. That Theresa May, who has long spoken of her desire to curb immigration, has backed Remain is a demonstration that more is at stake than reducing newcomers. Her absence deprived the Leave side of the executive authority it needed to make the reverse argument. The 2015 general election, which saw the Tories win a majority by emphasising the economy and downplaying immigration, is a measure of the challenge facing the EU's opponents. The more the Brexiters play the migration card, the greater the risk that they animate their core voters while alienating others. It was for this reason that Vote Leave resolved to run an optimistic campaign, non-centred on immigration. Gove's rhetorical escalation shows that they are struggling to abide by this vow. In raising the salience of immigration, Leave is playing to its strengths. Until it is able to neutralise its weaknesses, that will remain a displacement activity. › In Annie Baker’s The Flick, we watch people watching movies George Eaton is senior online editor of the New Statesman. Subscribe For daily analysis & more political coverage from Westminster and beyond subscribe for just £1 per month!