Senate leaders have reached a deal to revive debate on comprehensive immigration reform, including a provision that could provide millions of illegal immigrants a path to U.S. citizenship.

The deal reached Thursday by Senate Majority Leader Bill Frist and Minority Leader Harry Reid breaks a weeks-long political stalemate.  Frist said the Senate would resume debate sometime next week.

The key to the deal was agreement on which senators will get to negotiate with the U.S. House of Representatives to try to reconcile differences with their bill.

The House passed a tougher measure in December that would make illegal immigration a felony and construct a fence along a large section of the U.S.-Mexican border.

Immigration reform is looming as a key issue in this year's congressional election, in which Republicans are seeking to hold on to their majorities in both houses of Congress.

Republicans are divided on the issue, with some wanting to crack down on the more than 11 million illegal immigrants in the U.S. and others wanting to offer them a path to citizenship.

The debate has sparked massive demonstrations across the United States, including one earlier this year in Los Angeles, California that drew some 500,000 people supporting immigrants rights.