I think they should all get away from 'net' immigration. That is the figure when they subtract those going out compared with those coming in. As Labour's policies get more extreme it forces many more to leave these shores which creates a better impression of their ability to handle the crisis as the net figure will be lower.
The term net immigration is a farce because those leaving are usually white and better educated whilst those coming in are mostly the opposite which is changing the whole character of this country.
Tory - will be a bit stricter than Labour but not much
Lib Dem - may be a bit stricter than Labour but not much
A vote for any of the three main parties is a vote saying you accept their current stance on immigration.
The ONLY way to frighten these 3 parties into doing something about the scandal of immigration is to vote for a party that has it high on their list of priorities - UKIP and BNP.