Home Secretary Theresa May is due to formally announce the UK's first immigration cap.
Ms May is to introduce a temporary limit on non-EU arrivals to prevent a "surge" in the run-up to the introduction of a permanent maximum next April.
She will also give details of the process for deciding what the level of the cap should be after that time, and whether some sections of the economy should be given exemptions.
The immediate restrictions will mean that just 24,100 workers from outside Europe can enter the country before April 2011 - a fall of 5% on last year.
But there is speculation that Ms May has already been forced to water down the proposals for the permanent cap.
Some senior Tories are understood to have privately raised concerns about the impact on businesses seeking to recruit highly-skilled staff, while the Liberal Democrats opposed the idea during the General Election.
Speaking on the BBC's Andrew Marr show yon Sunday, Lib Dem Business Secretary Vince Cable stressed the Government had to "reassure the public" there was an effective system of immigration controls in place, but also ensure the economy was not damaged as it seeks to recover from recession.
"The new regime has to accommodate those concerns," Mr Cable said. "It has to be implemented in a flexible way."