Chuck Hagel, President Obama’s choice for Defense Secretary, is at risk of not being confirmed, thanks to a potential Republican filibuster—just weeks after Senate Democrats backed down in their bid to make such filibusters far harder. That’s got progressive activists who pushed for reform telling Harry Reid and co.: ‘We told you so.”

Last month, a group of Democratic senators, backed by a coalition of leading progressive groups, tried to significantly scale back the use of the filibuster, which in recent years the GOP has abused to grind the Senate to a virtual halt. But Reid, who had once embraced the reforms, appeared to lose his nerve, instead forging a deal with Republicans on a much weaker set of changes.

Advocates of reform warned at the time that the pact didn’t go nearly far enough. And now they tell msnbc.com that the showdown over Hagel proves they were right—and underlines why real reform is still needed.

“This is a perfect illustration of why we needed true filibuster reform,” Diana Kasdan, a lawyer at the Brennan Center, which backed the reform effort, told msnbc.com. “This is exactly what we feared.”

Sen. Jeff Merkley, who led the push to overhaul the filibuster, sounded a similar note in a statement released Thursday afternoon. “Merely weeks after the Senate came together in a good-faith effort to fix the Senate’s problems, Senate Republicans are now engaging in the first-ever filibuster of a Secretary of Defense nominee,” said Merkley. “It is deeply disappointing that even when President Obama nominates a former conservative colleague of the GOP caucus, the minority is abusing the rules and the spirit of ‘advise and consent.’ If our step we took last month is to be successful, extraordinary stunts like today’s filibuster can’t happen.”

Nan Aron, the president of Alliance for Justice, a liberal group that focuses on the justice system and also joined the reform push, also piled on “If this keeps up, Democratic leaders may need to assess whether the spirit of the recent rules reform deal has already been violated and revisit the need for the kind of far-reaching changes reformers called for in January,” Aron said in an emailed statement.

Republicans have said they plan to filibuster Hagel’s nomination unless the administration provides more details on past speeches he gave, and on its response to the Benghazi attacks. It would be the first time a Secretary of Defense nominee has ever been filibustered. And it means Reid would need 60 votes to get Hagel through.

Three Republicans have said they’ll vote for cloture—that is, vote to break a filibuster—on Hagel: Senators Mike Johanns, Susan Collins, and Thad Cochran. Added to the Senate’s 55 Democrats, that gives Reid 58 votes. It’s unclear whether he’ll be able to muster two more.

Under the stronger set of reforms that Aron and others were pushing, Republicans still would have been able to mount a filibuster against Hagel. But the burden to sustain it would have been on the minority senators, not on Reid and the majority, as it is now. That means Republicans would have had to keep 41 senators in Washington on the floor, and make an ongoing public case for why keeping the Pentagon without a leader was an issue of such importance—making it far more likely that Hagel would ultimately have received an up-or-down vote.

“It would have reduced the purely obstructionist tactics,” said Kasdan. “You would have had to be quite strategic and selective about the political costs involved.”

On the Senate floor Thursday morning, Reid lashed out at the GOP. ”There are serious consequences to this delay,” Reid said. “It sends a terrible signal not only to our military personnel but to the world…For the sake of our national security it’s time to put aside this political theater.”

But strong words from Reid don’t figure to have much impact. Instead, reform advocates say, the issue needs to be revisited to ensure that the Senate can function properly.

“Without rules reform that really imposes a cost on doing the filibuster, you’re going to see this continuing abuse,” said Kasdan.

Late Update, 2:51 p.m.: Sen. John McCain now says the White House’s responses on Benghazi were adequate and he is now working to “smooth this thing out and get it done,” bolstering hopes that Hagel will ultimately be confirmed.

Late Late Update, 5:12 pm: The AP reports: ”Republicans have, for now, blocked Chuck Hagel’s nomination to become defense secretary. The Senate came up two votes short of the 60 needed to move Hagel’s nomination forward as lawmakers prepare to leave town for a week’s break.” But Democrats say they expect Hagel to be confirmed after the recess.