It’s time — long past time — for Harry Reid and Senate Democrats to start fighting back against filibusters on executive branch nominations. It’s time to threaten to go nuclear.

If Republicans are determined to abuse Senate rules by using the filibuster to disable federal agencies, then Democrats should threaten to get rid of the filibuster.

As Ezra Klein highlighted this morning, Senate Republicans aren’t just threatening to block liberal fave Elizabeth Warren if she’s nominated to head the new Consumer Financial Protection Bureau; they’re vowing to filibuster any nominee unless Barack Obama and the Democrats agree to rewrite the agency’s charter. As Klein says, “It’s rare for parties to attempt root-and-branch reform of an agency from the minority position.”

But of course it’s not just the CFPB where Republicans are using the filibuster to insist on broad policy changes. They’re using the same tactic against various appointments needed to get Affordale Care Act up and running; they’re even blocking Obama’s nominee for Commerce Secretary.

Democrats have responded by…well, I have no idea. I’m hearing minimal, if any, howls of outrage; I’m not seeing Obama elevate the issue. Mostly, what I hear is resigned frustration. They seem to be acting as if 60 votes for all nominations is just the normal way the Senate conducts business. It isn’t.

Or, at least, it wasn’t until January 20, 2009. Yes, there have been party-wide filibusters of executive branch nominees in the past, but it’s almost always been about specific people who the president could withdraw and replace. Holds placed by individuals or small groups of Senators in order to get leverage over a specific grievance — usually some home-state interest — are common, and every Senator has an interest in preserving that procedure, whether outsiders like it or not. But a party-wide decision to simply not confirm anyone for a variety of positions? I’m not sure if it’s ever been done before by a majority party during periods of divided government, let alone by the minority party.

What Reid and the Democrats should be doing is threatening dramatic action: eliminating supermajority rules for executive branch confirmation. The truth is they should probably threaten to just get rid of filibusters altogether. But that’s a tall order. For now, it should be doable to get every Democrat to support making it possible to confirm executive branch nominations with a simple majority of Senators. Doing so would simply return the Senate to how it was governed throughout its history up until the Obama presidency. Dems would simply be threatening to restore the old norm that while the Senate could influence policy, the president was, barring exceptional circumstances, entitled to the person he wanted to carry out that policy.

There’s nothing to prevent the Senate from changing its rules by majority vote. There’s considerable debate among Congressional scholars about exactly how to go about it, but the bottom line is that if the majority can do it if they really want to.

You’ll recall that the parties struck a deal at the beginning of the current Congress in which the Democrats dropped plans for significant filibuster reform in exchange for Republican restraint in exploiting the rules. My impression on judicial nominations is that the deal has basically been a modest success: Republicans appear to no longer be filibustering every single judicial nomination. However, on executive branch nominations the situation, if anything, appears to be getting even worse.

I’m not a fan of the common liberal critique that Democrats would win more battles if only they had more backbone. If the votes aren’t there, you can be as tough as you want and it won’t do much good. But in this case, it rings true. Harry Reid may or may not really have the votes to turn the Senate into a majority-run institution for everything — but he certainly should have the votes to do so on executive branch nominations. Going nuclear on those should be a credible threat. It can be explained as a return to true Senate tradition. And if the threat isn’t enough, Reid should pull the trigger.