The prime minister is setting out plans to curb welfare benefits for migrants from the EU.
David Cameron will say EU migrants should have to wait at least four years before receiving benefits such as tax credits or council houses.
He will insist the changes, which he will seek if he is elected in May, are an "absolute requirement" in future talks over whether to stay in the EU.
It follows news that net migration to the UK has risen above 2010 levels.
In a long-awaited speech in the West Midlands, Mr Cameron will say he is confident that he can change the basis of EU migration into the UK and therefore campaign for the UK to stay in the EU in a future referendum planned for 2017.
But he will warn that if the UK's demands fall on "deaf ears" he will "rule nothing out" - the strongest hint to date he could countenance the UK leaving the EU.
The main proposals in the speech - which are dependent on Mr Cameron remaining in power after May's general election - are: