By Thomas Ferraro
WASHINGTON, Jan 24 (Reuters) - U.S. Senate leaders reached a deal on Thursday aimed at easing gridlock by modifying rules that have been blamed for making their bitterly partisan chamber a legislative graveyard.
But the accord falls far short of what some reformers wanted by preserving the right of a minority of senators to stop legislation with procedural roadblocks known as filibusters.
Majority Leader Harry Reid, a Democrat, and Minority Leader Mitch McConnell, a Republican, reached the deal after weeks of negotiations.
Under the agreement, 60 votes in the 100-member chamber would still be needed to end a filibuster despite calls by some lawmakers to lower the figure.
A number of Democrats complain that existing rules have let Republicans block much of President Barack Obama's agenda with as few as 40 votes.
The deal would stop filibusters aimed at blocking legislation from reaching the Senate floor by guaranteeing that the minority party gets to offer at least two amendments. But a minority of lawmakers could block a bill after that point.
The compromise is expected to avert a partisan struggle that could have tied the Senate into knots just as Obama begins his second term.
Reid and McConnell were to present their deal to members later in the day for anticipated approval, aides said.
The filibuster is an old Senate tool that lets opponents of legislation delay or kill legislation by threatening to deliver non-stop speeches that can only be stopped by a three fifths-vote.
Democrats are split on the issue, with a number wanting to keep the 60-vote threshold on filibusters, reasoning that at some point they will be in the minority.
(Reporting By Thomas Ferraro; Editing by Fred Barbash and Vicki Allen)