Can David Cameron reverse the immigration trend?

The prospect of reducing net migration to the tens of thousands is more distant now than it was when David Cameron first entered Number 10.

Having renewed his commitment to this "ambition" in the Conservative manifesto, he must now try to reverse a trend.

The government signalled its intent with a photocall this morning at the scene of an immigration raid, publicising a law designed to hit illegal migrant workers in the pocket.

Success or failure, though, will be dictated by reducing legal migration.

The prime minister believes better-trained Britons, more apprentices, and new EU welfare rules will help achieve that.

His decision to chair a taskforce on the topic is intended to focus minds in Whitehall.

But while crackdowns, legislation and declarations of intent make good copy, there is no guarantee they will shift the figures.

The UK cannot dictate how many EU citizens come here, or how many Britons leave.

Businesses will worry that by targeting the sort of immigration they can affect - legal migrants from outside the EU - ministers risk making it harder to hire skilled workers.

No law can change the fact there are more jobs and better pay in Britain than in many other nations.

Migrants will still want to come.

But Conservatives are keenly aware that there could be a heavy political price to pay if they go into a second election having conspicuously failed to realise their ambition.