Senior Senate Democrats recently launched a rearguard attempt to regain power they’d lost in December but were repelled by new members of the Senate in an overlooked but potentially consequential internal caucus battle.

In December, Chris Murphy, the junior Democratic senator from Connecticut, pushed for and won a change to caucus rules that would strip power from the chairs of the most important committees. (Caucus rules can be amended by a majority vote of the caucus.) Then in January, senior Democrats attempted to delay the implementation of Murphy’s rules change and were unsuccessful. Multiple Senate sources, who spoke anonymously to be candid about internal politics, told The Intercept that the discussion was contentious.

Murphy’s success is part of a larger shift in power toward more recently elected Democrats in the caucus, reflecting the rise of members less yoked to the mythology of the Senate as a haven of deliberation and bipartisanship. New members of the party drove partial reform of the filibuster in 2013 and are now pushing to go further, arguing that Republicans are not and won’t ever be willing to be reasonable negotiating partners and that the filibuster should be completely eliminated.

Under the previous Democratic caucus rules, committee gavels were doled out by seniority, and those chairs then had first dibs on the most prized subcommittees as well — meaning that senior members could control the flow of legislation through the committee from beginning to end, or could chair a key policy committee, while also chairing the appropriations subcommittee that funded that policy area, giving them additional influence.

In December, Murphy and his colleagues argued that the double-dip of power was too much and proposed a rule that committee chairs couldn’t have their pick of select subcommittees until everyone else in the caucus had a shot. Senior members pushed back, led by Sens. Patrick Leahy, elected in Vermont in 1974 and serving as chair of the Appropriations Committee; Patty Murray, elected in Washington in 1992 and serving as chair of the Health, Education, Labor, and Pensions Committee as well as holding a leadership position; Tom Carper, elected in Delaware in 2000 and serving as chair of the Committee on Environment and Public Works; and Jack Reed of Rhode Island, elected in 1996 and serving as chair of the Armed Services Committee.

In addition to their prime committee gavels, Murray and Reed also serve on the Appropriations Committee and would have been in line for powerful subcommittee spots. Carper also serves on the Finance Committee and Homeland Security Committee.

Despite the high-powered pushback, the caucus voted to approve Murphy’s change. Sen. Amy Klobuchar, D-Minn., meanwhile, pushed a rules change that would limit the time a chair could serve to a six-year term, according to sources in the meeting. That effort was defeated, considered by enough of the caucus to be too strict a limitation on seniority rights. (Republican Senate chairs have term limits, though Democrats do not.)

But senior members of the party continued to fight the change, bringing it to another vote in late January at a caucus meeting and arguing for a two-year delay in implementing the new rule. Sens. Jon Tester of Montana (elected in 2006), Martin Heinrich (2012) of New Mexico, and Chris Van Hollen (2016) of Maryland, along with Murphy (2012), all argued against delay.

Passions were high on both sides, said one person on the call. Again, the caucus sided with Murphy and the newer members of the Senate.

The votes were cast by secret ballot, but senators were told by leadership that the tally was “decisively” in favor of moving forward immediately with Murphy’s reform — a Senate version of the Confucian proverb that no one deserves a second bowl of rice until everyone has had a first.

The rules change and the effort behind it have a variety of implications beyond the shuffling of gavels. On the internal politics front, it suggests that Murphy’s cache among his colleagues is rising. The change also empowers newer members of the caucus but does so at the expense of the chairs of powerful committees, which in turn increases the relative power of the party’s leadership — inching forward the steady evolution of the upper chamber from one that originally had no Senate majority leader to one in which the position was ceremonial, to an institution with a powerful leader who can guide the chamber’s agenda.

Until 1925, the Senate operated without the position of majority leader. The chamber was instead run by “old bulls” who climbed the ranks of committees by virtue of how long they’d been in the Senate. Legendary senators like Henry Clay, W-Ky., Daniel Webster, W-Mass., and Stephen Douglas, D-Ill., enacted their will through coalitions, their control of key committees and voting blocs and, in the case of Douglas, obscene amounts of bribery.

Through much of the New Deal, Senate Majority Leader Alben Barkley, D-Ky., was considered a foot soldier for President Franklin D. Roosevelt, earning the moniker “Dear Alben.” When Sen. Richard Russell, D-Ga., wielded vast power over the chamber, he did so without ever seeking the post of majority leader. Texas Democrat Lyndon Johnson became majority leader in 1955 with little opposition, as the position was considered largely ceremonial. He used what tools it did have to shape the post into a powerful perch, beginning the trajectory that continues today. That trend has combined with the sorting of the parties along ideological lines in a way that is new to American politics, and the resulting partisan behavior has further entrenched the power of the majority leader.

The relative increase of the leader’s authority, compared to the committee chairs’, resulting from Murphy’s rule is marginal, and Senate Majority Leader Chuck Schumer, D-N.Y., remained neutral in the fight, allowing the caucus to sort it out, sources involved in the debate said.

Murphy, Tester, Heinrich, and Van Hollen all serve on the Appropriations Committee, and the new rule moves them closer to chairing key subcommittees there. Tester, given his seniority, was already in line for a subcommittee gavel, but Leahy, Reed, and Murray will be nudged aside on subcommittees where they were in line to take over, respectively: State, Foreign Operations, and Related Programs; Transportation, Housing and Urban Development, and Related Agencies; and Departments of Labor, Health and Human Services, and Education, and Related Agencies. Murray’s subcommittee gavel combined with her Health, Education, Labor, and Pensions Committee post gave her a particularly consolidated position.