WASHINGTON — Business and labor groups announced agreement Thursday on the principles of a new system to bring lower-skilled workers to the United States, a key priority for a comprehensive immigration bill.

The US Chamber of Commerce and the AFL-CIO reached consensus after weeks of closed-door negotiations they were conducting at the request of Senators Charles Schumer, Democrat of New York, and Lindsey Graham, Republican of South Carolina, two of the senators involved in drafting an immigration deal on Capitol Hill.