Two Republican senators proposed steps to slash the number of legal immigrants admitted into the United States by half on Tuesday, but the legislation, developed with the Trump administration, faces an uphill climb to get through Congress.

Sens. Tom Cotton and David Perdue said their bill would cut the number of immigrants granted U.S. residency each year to 500,000 from 1 million, through measures including cutting far back on which relatives can be brought into the country and eliminating a diversity visa lottery.

The legislation would not affect foreigners admitted to the United States on visas specifically tied to their employment.