As Ken Clarke has told colleagues, the problem is that Labour — albeit right at the end of their time in office — stopped non-EU low-skilled immigration. So all there was left to cap was high-skilled immigration.
But there is a potential solution that would enable the cap — a Conservative manifesto promise — to remain in place, but also deal with Vince Cable and businesses’ objections http://www.thisislondon.co.uk/standard-business/article-23879244-vince-cables-attack-on-immigration-cap-wins-city-backing.do.
One compromise could be that workers could be brought in over the cap if they or their employer paid a deposit of £30,000, refundable when they have paid that amount in income tax and national insurance. Considering the jobs that most of these workers are coming here for, this deposit would be earned back quickly.
Given what I have heard recently, I suspect most businesses would be happy with this. While the Conservatives would still be able to tell the voters that they had introduced a cap.