Senate Democrats passed a major rules reform Thursday further dividing an already fractured Senate.

Sen. Majority Leader Harry Reid, D-Nev., stopped threatening and finally invoked the so-called nuclear option — a rules change that requires a simple 51-vote majority on certain presidential appointments.

The new reform allows senators to approve the president's judicial and executive nominees with a simple majority vote instead of the 60-vote threshold previously required. Supreme Court nominees will continue to require 60 votes.

"It's time to get the Senate working again, not for the good of the current Democratic majority or some future Republican majority, but for the good of the country. It's time to change the Senate, before this institution becomes obsolete," Reid said on the Senate floor Thursday.

Sens. Carl Levin, D-Mich., Mark Pryor, D-Ark., and Joe Manchin, D-W. Va., were the only Democrats to vote against the rules change.

The decision to revise Senate procedure came after Republicans blocked three presidential appointees.

Republicans accused the Obama administration of filling the U.S. Court of Appeals for the District of Columbia Circuit with liberal judges who would uphold Obama's agenda. Democrats accused Republicans of blocking qualified candidates.

President Barack Obama addressed reporters at the White House Thursday after the vote, endorsing Senate Democrats' effort.

"The vote today I think is an indication that a majority of senators believe, as I believe, that enough is enough," Obama said. "The American people's business is far too important to keep falling prey, day after day, to Washington politics."

One of the Republican Party's top deal makers, Sen. John McCain, R-Ariz., who has stopped the "nuclear option" in the past, spent two weeks negotiating with Democratic leaders, but fell short.

McCain told reporters Thursday that young Democrats, who did not understand the burden of being in the minority, were responsible for the "foolish" rules change.

Republican Minority Leader Mitch McConnell, R-Ky., told reporters Thursday that it was a "sad day" for the Senate.

Former Sen. Olympia Snowe, R-Maine., who has been lauded as a moderate problem solver in the Senate, released a statement Thursday warning the rule reform could further polarize Congress.

"Today's historic change to Senate rules escalates what is already a hyper-partisan atmosphere in Washington, which is already preventing Congress from addressing our nation's most significant challenges," she said in a statement.