As Capitol Hill continued to reel Wednesday from the news that President Donald Trump had fired FBI Director James Comey, Democrats scrambled to respond to what some of them are calling a constitutional crisis.

Calls for the appointment of a special prosecutor to take over the Russia investigation Comey was leading grew louder from Democrats and a small handful of Republicans, who say it’s the only way to prevent the inquiry from being compromised going forward. And while they’re in the minority in the Senate as well as the House, Democrats decided to flex their muscle with a series of procedural moves to grind the upper chamber’s work to a halt—canceling or delaying all committee meetings for the rest of the day.

Sen. Jeff Merkley (D-OR) said the aim of the tactic was to force lawmakers from both parties to come together for an emergency meeting on the future of the FBI’s probe into whether Trump campaign officials colluded with Russian officials.

“We need to fight for the integrity of our system of government,” he told TPM. “We need to come together in the very near future for an executive session of the Senate to have a heart-to-heart discussion on how to defend our democratic republic. We need to reach an agreement on a strategy to ensure a fully-funded, aggressive investigation of not just Russian activity but any coordination or collaboration by any members of the Trump campaign. If there was such coordination that would be a treasonous crime.”

But such bipartisan talks have yet to materialize, and some Republicans were openly frustrated by the Democrats’ stalling tactics.

Sen. Susan Collins (R-ME) complained on the Senate floor that a hearing on aging Americans had been postponed.

“I am baffled by this,” she said. “This has nothing to do with the firing of Jim Comey. It has nothing to do with the intelligence committee’s ongoing and successful investigation of Russian influence on our election. It has nothing to do with the health care debate that is roiling this Congress. This is a hearing that has to do with the health and well-being of America’s seniors. It is not political in any way.”

An hour later, Sen. Steve Daines (R-MT) joined the chorus of protest, lamenting that a Energy and Natural Resources subcommittee hearing on rural water systems had fallen victim to the work stoppage.

“They’re choosing to play politics and prevent scheduled meetings from occurring,” he said of Democrats, noting that some of the committee’s scheduled witnesses had traveled thousands of miles to attend.

But Democrats argued that desperate times call for desperate measures.

“Today is certainly not business as usual,” Sen. Mazie Hirono (D-HI) told TPM. “There should be a drumbeat building for a bipartisan call for a special prosecutor to get to the bottom of Russian interference in our democracy—their attempts to screw our democracy.”

“I should think that Republicans would care. I’m sure in their heart of hearts they do,” she added.

Senate Democrats have not yet revealed if they plan to continue their delay tactics in the days and weeks ahead, potentially holding up votes on dozens of bills and nominees for various agency positions.

“I can’t say it’s an ongoing strategy,” Sen. Dianne Feinstein, the ranking member of the Judiciary Committee, told the Washington Post. “It certainly is for the day.”

Hirono was similarly coy about future tactics. “Let’s just take it one day at a time,” she told TPM.

But Merkley and other Democrats talked openly about the need to escalate going forward if Republicans refuse to collaborate.

“If we don’t have a briefing by early next week, if we don’t have an executive session, if we don’t reach an agreement on the vision for a special prosecutor, we’re going to have to crank up the pressure,” he said.