Donald Trump and his aides are quietly working with two conservative senators to dramatically scale back legal immigration — a move that would mark a fulfillment of one of the president’s biggest campaign promises.

Trump plans to get behind a bill being introduced later this summer by Sen. Tom Cotton (R-Ark.) and Sen. David Perdue (R-Ga.) that, if signed into law, would slash in half the number of legal immigrants entering the country each year by 2027, according to four people familiar with the conversations. Currently, about a million legal immigrants enter the country annually, and that number that would fall to 500,000 over the next decade.

The senators have been working closely with Stephen Miller, a senior White House official known for his hawkish stance on immigration. The issue is also a central priority for Steve Bannon, the president’s chief strategist, who has several promises to limit immigration scribbled on the walls of his office.

The forthcoming bill is a revised and expanded version of legislation the two senators unveiled in February, known as the RAISE Act, which they discussed with Trump at the White House in March, and which the president praised at the time.