THE DRIVE FOR SENATE REFORM PICKS UP STEAM…. For quite a while, senators hoping to change their dysfunctional institution have generally been part of a small, almost quixotic, group. The issue of reforming the Senate’s easily-abused, often-archaic rules just hasn’t been high-profile enough to generate widespread enthusiasm.

But the salience of Senate reform appears to be growing. This week’s developments within the Democratic caucus were a huge step in the right direction.

All Democratic senators returning next year have signed a letter to Senate Majority Leader Harry Reid, D-Nev., urging him to consider action to change long-sacrosanct filibuster rules.

The letter, delivered this week, expresses general frustration with what Democrats consider unprecedented obstruction and asks Reid to take steps to end those abuses. While it does not urge a specific solution, Democrats said it demonstrates increased backing in the majority for a proposal, championed by Sen. Tom Udall, D-N.M., and others, weaken the minority’s ability to tie the Senate calendar into parliamentary knots.

Among the chief revisions that Democrats say will likely be offered: Senators could not initiate a filibuster of a bill before it reaches the floor unless they first muster 40 votes for it, and they would have to remain on the floor to sustain it. That is a change from current rules, which require the majority leader to file a cloture motion to overcome an anonymous objection to a motion to proceed, and then wait 30 hours for a vote on it.

The only Democratic senator to withhold his signature from the letter was Connecticut’s Chris Dodd, who isn’t coming back next year anyway.

The unanimity matters a great deal. There have been a handful of senators working behind the scenes on reform efforts for months, with the bulk of the work being done by newer, younger members like Merkley, Udall, Bennet, Warner, and McCaskill. (The exception is Iowa’s Tom Harkin, who’s been a leader on this for many years.)

But this week’s letter was signed by every Dem who’s returning for the 112th Congress. It suggests the unprecedented obstructionism from Republicans in recent years has made it overwhelmingly clear — this isn’t how the Senate used to work, this isn’t how the Senate was designed to work, and this isn’t how the Senate should be expected to work.

Obviously, the details of reform make all the difference, and there’s no real agreement, even among Dems, about exactly which reforms to push. It’s also not clear how Democrats would pursue potential changes procedurally.

Still, it’s encouraging that the issue is generating some momentum going into the new year. At least in theory, the larger dynamic might even make Republicans more amenable to change — even if Dems found it easier to pass bills next year, there’s still a very right-wing House to block measures the GOP doesn’t like. And since Republicans hope/expect to win back the Senate in 2013 anyway, this may be a unique moment for bipartisan progress.

Post script: Chris Hayes had a good item on this yesterday, noting, among other things, that earlier this week, former Sens. Chuck Hagel (R-Neb.) and Gary Hart (D-Colo.) issued a bipartisan call for rules reform. “The most important vote of the 112th Senate will likely be its first,” Chris concluded.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.