As one Republican senator launched a “talking filibuster” Wednesday, the No. 2 Democratic leader in the Senate signaled it may already be time to reopen debate about the chamber’s rules.

In the month and a half since the chamber approved modest filibuster rule changes, Republicans have attempted to filibuster three presidential appointments, Senate Majority Whip Richard J. Durbin, D-Ill., noted.

“We have tried at the beginning of this Senate session to avoid this kind of filibuster confrontation. The last several years we have had over 400 filibusters — a record number of filibusters in the Senate,” Durbin said.

At the start of this Congress in January, Senate leaders reached a bipartisan agreement to slightly alter the chamber’s rules in a bid to make the Senate work more efficiently. None of the rules changes affected circuit court or Cabinet appointees, and at most, the changes merely reduced the amount of time any senator could hold up a vote on whether to proceed with a filibuster. In no case was the ability to filibuster eliminated.

“I hate to suggest this, but if this is an indication of where we’re headed, we need to revisit the rules again,” the Illinois Democrat said. “We need to go back to it again. I’m sorry to say it because I was hopeful that a bipartisan approach to dealing with these issues would work.”

Just hours after Durbin made his comments, Republican Sen. Rand Paul of Kentucky took the floor to “actively filibuster” the nomination of John O. Brennan to be the next CIA director. Paul pledged to talk as long as possible to express opposition to the Obama administration’s policy regarding targeted killing of American citizens using drones.

Paul’s speech came shortly after Senate Republicans successfully led an effort to filibuster the nomination of Caitlin J. Halligan to the U.S. Court of Appeals for the District of Columbia Circuit. Halligan has been one of the most contentious nominees of President Barack Obama’s tenure. In 2011, she failed to garner the 60 votes needed to overcome Republican opposition, but Obama renominated her this year. On Wednesday morning, 60 votes were needed to advance her nomination, but she was blocked on a 51-41 vote.

Liberal groups outside the Senate were furious with Majority Leader Harry Reid, D-Nev., and other Democrats for what they view as a failure to make good on threats to use the “nuclear option” to change the rules. Though Senate rules state two-thirds of the chamber are needed to overcome a filibuster of a rules change, Reid had contemplated using an option promoted by Democrats that would have allowed him to alter the filibuster rules at the beginning of the Congress by a simple-majority vote.

“We saw this morning another glaring example of anti-democratic rule by a minority in the United States Senate,” Common Cause President Bob Edgar said. “A bipartisan majority supported this nomination, but a minority barred them from approving her with another filibuster.”

Sen. Tom Udall, D-N.M., had pushed a rules change package that included a way to get to get around filibusters with a simple majority and a requirement that senators talk on the floor to maintain a filibuster, as Paul did Wednesday afternoon.

Udall demurred on Wednesday until he could discuss the matter with Durbin, but he did say: “We’re always in the middle of the rules debate.”

Republicans sought to tamp down the suggestion that a Halligan filibuster demonstrated an issue with the rules. Sen. Kelly Ayotte, R-N.H., noted that “very few” Circuit nominees had faced opposition to the extent faced by Halligan, and Sen. John McCain said he applied an old test to her nomination.

“We had a provision for extraordinary circumstances in the gang of 14,” the Arizona Republican told reporters. “This is an extraordinary circumstance.”

McCain was referring to a provision in the 2005 agreement between seven Democrats and seven Republicans that prevented then-Majority Leader Bill Frist, R-Tenn., from using a similar “nuclear option” to change the rules related to judicial nominations. The senators agreed not to vote against cloture on judicial nominees except in “extraordinary circumstances.”

Senate Judiciary Chairman Patrick J. Leahy, D-Vt., disputed that idea.

“Republican Senators who were part of the gang of 14 just a few years ago, others who said they would never filibuster a judicial nominee, those who said that they would only filibuster in extraordinary circumstances, and all those who insisted on pushing through President Bush’s most extreme ideological nominees have now all reversed themselves to the detriment of the courts and the country,” Leahy said.

Senate Minority Leader Mitch McConnell reiterated his opposition to Halligan on Wednesday morning.

“Many of our Democratic colleagues who are expressing shock and utter amazement that we would deny cloture on Ms. Halligan’s nomination a second time felt absolutely no compunction about repeatedly denying cloture on Miguel Estrada’s nomination to the same court,” the Kentucky Republican argued.

In invoking Estrada’s name, McConnell is connecting Halligan to the most famous of the judicial nomination feuds during the George W. Bush administration.

Still, Durbin said that the procedural blockades erected on the nominations of both Halligan and Defense Secretary Chuck Hagel (who was eventually confirmed when a handful of Republicans declined to continue the filibuster) have left him with serious doubts that the bipartisan agreement on modifying the Senate’s rules is working as intended.

“We had the first filibuster in history of a secretary of Defense nominee, the first,” Durbin said. “And now we follow with this filibuster of this D.C. Circuit nominee. I don’t think we’ve achieved much in our rules reform. I don’t think our spirit of bipartisanship has shown much in terms of results.”