A bipartisan group of senators on Tuesday introduced a bill outlining a sweeping overhaul of the US immigration system, aiming to shift its focus towards skilled workers who will boost the economy by setting up a new points-based “merit” system for awarding visas.

The draft bill creates “triggers” that require improvements in border security to be under way before the 11m undocumented immigrants in the US can begin the process of becoming legal residents – a key Republican demand.

Under the proposals, undocumented immigrants who were in the country before 2012 will be able to apply to for “registered provisional immigrant” legal status after they pay a $500 fine and back taxes, and as long as they have not committed a felony offence or three misdemeanours.