The remarks – which echo arguments Ornstein and Mann published earlier this year in their book "It's Even Worse Than It Looks" – arrived as lawmakers are ramping up the partisan debate over how to approach looming, end-of-the-year deadlines on a whole host of thorny tax and spending issues.

Those policy changes – collectively deemed the "fiscal cliff" – include expiration of the Bush-era tax rates, a sharp reduction in Medicare payments to doctors, the end of the payroll tax cut for all workers and steep cuts to defense and domestic spending that Congress approved as part of last year's sequester arrangement.

A long list of economists, including Federal Reserve Chairman Ben Bernanke, have warned that allowing those fiscal changes to take effect next year could send the country back into recession.

Congress has been unable to reach agreements on how to avoid the cliff, and Democrats used Ornstein and Mann to argue Republicans are to blame.

Republicans have been quick to blame President Obama and the Democrats for the sequester cuts. They say the Democrats haven't taken those cuts seriously, instead holding the threatened programs "hostage" to the Democrats' proposal to hike taxes on the wealthiest Americans in January.

"This administration has failed to respond to our repeated requests to come to the table to see if we can resolve this so that the sequester doesn’t hit," House Majority Leader Eric CantorEric CantorWhat to watch for in Comey’s testimony Trump nominates two new DOD officials Brat: New ObamaCare repeal bill has 'significant' changes MORE (R-Va.) told reporters Wednesday.

The sequester was included in August's debt-ceiling agreement, the Budget Control Act (BCA), as an enticement for the fiscal supercommittee – a 12-member bipartisan panel also created by that law – to forge an alternative deficit reduction strategy.

When the supercommittee failed in that effort, they triggered the sequestration mechanism, which will cut $1.2 trillion to defense and domestic programs over 10 years unless Congress acts first.

Democrats have pushed back against the GOP criticisms, noting that Republican leaders also voted in favor of the BCA.

"The Budget Control Act was strong medicine, but it was bipartisan," Rep. Xavier BecerraXavier BecerraGingrich: Media was right, special elections were a referendum California’s newest rep. promises 'hard stance' against Trump agenda Dem AGs, green groups sue Trump over paused energy efficiency rules MORE (Calif.), vice chairman of the House Democratic Caucus and a member of the supercommittee, told reporters Wednesday. Congress, he added, has devolved into "a partisan workshop."

Rep. John Larson (Conn.), chairman of the House Democratic Caucus, hammered GOP leaders for creating "an artificial issue" by opposing a clean debt-ceiling hike – opposition that eventually led lawmakers to attach the supercommittee and sequestration provisions to avoid a government default.

"There are consequences to be paid [for opposing a clean bill]," Larson said.

Ornstein on Wednesday said the failure of the supercommittee to reach a deal was foreshadowed by Senate Minority Leader Mitch McConnellMitch McConnellRocky rollout for Senate healthcare bill Overnight Healthcare: Latest on Senate healthcare bill | Four conservatives say they'll oppose | Obama slams bill | Health groups offer scathing criticism Sanders: I hope McConnell listened to protesters outside his office MORE's picks for the panel. If McConnell (R-Ky.) had chosen just one GOP member of the so-called Gang of Six – which included Sens. Tom CoburnTom Coburn'Path of least resistance' problematic for Congress Freedom Caucus saved Paul Ryan's job: GOP has promises to keep Don't be fooled: Carper and Norton don't fight for DC MORE (Okla.), Mike CrapoMike CrapoOvernight Regulation: Senate Banking panel huddles with regulators on bank relief | FCC proposes 2M fine on robocaller | Yellowstone grizzly loses endangered protection Overnight Finance: Big US banks pass Fed stress tests | Senate bill repeals most ObamaCare taxes | Senate expected to pass Russian sanctions bill for second time All big US banks pass Dodd-Frank stress tests MORE (Idaho) or Saxby ChamblissSaxby ChamblissOPINION: Left-wing politics will be the demise of the Democratic Party GOP hopefuls crowd Georgia special race Democrats go for broke in race for Tom Price's seat MORE (Ga.) – then "we've got a deal," he said.

"And he didn't – [he] studiously avoided them," Ornstein said, suggesting McConnell didn't want to reach a deal that would give Obama a huge political victory. "These guys are not moderates, or liberals. They're strong conservatives. But they wanted to solve the problem and recognized … that revenues have to be a component of it."

Mann noted another obstacle facing lawmakers hoping to avoid the fiscal cliff: Grover Norquist's anti-tax pledge, which most Republicans have signed, takes most new revenues off the table.

"The Republicans remain too dug in to their 'no-new-tax' pledge," Mann said. "That is the major obstacle" to a deal.

Even as Ornstein and Mann were teeing off on Republicans on the House side of the Capitol, McConnell was taking a few shots at the two political scientists from the Senate chamber. In a lengthy sparring match with Senate Majority Leader Harry ReidHarry ReidDems see surge of new candidates Dems to grind Senate to a halt over ObamaCare repeal fight GOP fires opening attack on Dem reportedly running for Heller's Senate seat MORE (D-Nev.) over McConnell's habitual use of the filibuster, the Kentucky Republican accused Ornstein and Mann of siding with the Democrats for ideological reasons.

"I actually know Norm Ornstein and Tom Mann," McConnell said. "They are ultra, ultra liberals. Their problem with the Senate is Democrats don't have 60 votes anymore."

Ornstein countered that there’s a difference between the two parties.

"There are no angels here. We're not saying we've got one terrific party and one awful party, and voters should throw out the awful ones and bring in the good ones," Ornstein said. "But there's a real difference now between the parties."