David Cameron has insisted it is "perfectly possible" to cut immigration to the tens of thousands a year.
MPs have cast doubt on whether a limit on numbers from outside the European Union can significantly reduce net migration from its current level of almost 200,000 a year.
But, in an interview with Sky News, the Prime Minister indicated he remained committed to more than halving immigration and insisted that it was achievable.
"If you stand back and look at the big picture, actually immigration between Britain and the rest of the EU is pretty much in balance," he said.
"It's between Britain and the rest of the world where it's got out of balance and we have this large level of net migration into the UK.
"That is partly economic migration. It's also about large numbers of people coming to settle in the UK. It's also about a lot of people abusing the student regime.
"So I think if you tackle all of those things it's perfectly possible - it's my ambition - to get to net migration from the rest of the world coming down to the tens of thousands rather than the hundreds of thousands."
The Home Affairs Select Committee warned recently that the cap would make little difference to overall immigration and could damage the economy.
It said fewer than one in 100 migrants entering the UK might be affected.