The new rules "get rid of the major roadblocks that have gridlocked this Senate," Sen. Carl Levin, D-Mich., who led negotiations with seven other senior senators on the bipartisan compromise, told reporters.
The measures -- passed Thursday evening in two separate votes, 78-16 and 86-9 -- preserve the filibuster but give the majority party several options for how to get bills to the Senate floor.
Right now, the minority party gets two opportunities to filibuster every bill, but the new deal could limit that to just one full filibuster, depending on circumstances.
Both parties will have a greater role in proposing bill changes, something senators have said party leadership often kept them from doing, The New York Times said.
Other changes include streamlining the nominating process for U.S. district court judges and low-level administration appointees to two hours from the 30 now allowed.
Many of the new provisions expire when the new Congress convenes in 2015.
But the deal -- worked out between Senate Majority Leader Harry Reid. D-Nev., and Minority Leader Mitch McConnell, R-Ky., after a bipartisan agreement among senior senators -- leaves many loopholes and sidesteps reforms critics said would have made the agreement historic, the Times said.
And it preserves an aspect of the Senate some critics say is peculiar -- the majority, currently Democratic, will still not have absolute rule. That's because the minority can still force a supermajority of three-fifths of the senators, or 60 votes, to advance bills.
"This is not significant," Sen. Tom Harkin, D-Iowa, told reporters. "It's a baby step. Really, it's a baby, baby step."
But freshman Sen. Elizabeth Warren, D-Mass., told the Times she considered the vote "some change in a Senate committed to no change, so that's important."
Reid told The Washington Post before the vote he was "not personally, at this stage, ready to get rid of the 60-vote threshold."
"With the history of the Senate, we have to understand the Senate isn't and shouldn't be like the House," he said.