The Senate voted Thursday to weaken the rules on filibusters of judicial and executive nominations -- a historic change that has Republicans outraged.
Presidential appointees must now be approved by a simple majority vote, rather than a two-thirds majority.
GOP lawmakers say Democrats have overturned nearly 200 years of legislative restraint, setting a dangerous precedent.
"Most important and most dangerous restructuring of Senate rules since Thomas Jefferson wrote them," Sen. Lamar Alexander, R-Tenn., charged.
Republicans call the move a power grab and warn it could result in the passage of controversial legislation in the future.
Meanwhile, President Barack Obama welcomed the change.
"I'm a former senator. So is my vice president," the president said. "We both value any Senate's duty to advise and consent. It's important and we take that very seriously."
"But a few now refuse to treat that duty of advise and consent with the respect that it deserves," he added. "It's no longer used in a responsible way to govern. It's rather used as a reckless and relentless tool to grind all business to a halt."
Eight years ago, however, then Sen. Obama argued against changing the filibuster rule.
"If the right of free and open debate is taken away from the minority party, and the millions of Americans who ask us to be their voice, I fear that the partisan atmosphere in Washington will be poisoned to the point where no one will be able to agree on anything," Obama said in 2005.
Democrats wasted no time putting the rule change into effect, moving forward on a judicial nominee who was blocked for almost six months.
Some warn that Senate Democrats could come to regret this move in the future when Republicans are in control.
"There will be another Republican president at some point, and that Republican president will have the same kind of discretion now that President Obama does to nominate judges," noted David French, senior counsel with the American Center for Law and Justice.
It also could be a serious blow to bipartisanship, making it even more difficult for both parties to work together in Washington.
Currently, the rule change only applies to presidential nominees. But conservatives warn that in the future it could lead to Obama packing the courts with left-wing judges.