With bipartisan comity at historic lows in the Senate, Democrats and Republicans are locked in an esoteric, rhetorical face-off over who is to blame for what could be a record number of filibusters in the 110th Congress.

Majority Leader Harry Reid (D-Nev.) appeared on the Senate floor with a large sign emblazoned with the number “72” on Monday — that’s how many times he said Republicans have blocked Democrats from acting on legislation.

Minority Leader Mitch McConnell (R-Ky.), on the other hand, said that number is just “patently not accurate, to use a nice word for it.”

“The truth is, there haven’t been 72 occasions upon which Republicans were trying to prevent legislation from going forward at all,” McConnell said on Tuesday. But he acknowledged, “There have been a few occasions when we have tried to do that.”

Republicans say they are, at most, responsible for 13 outright filibusters, where a bill, resolution or amendment died, never to see the light of day again. But even within that 13, they say, they had a little help at times from Democrats opposed to the measures as well.

At issue is the number of times the Senate has voted on time-consuming procedural motions to limit debate, or invoke cloture, in order to get past individual Senators’ objections to bills. Sixty votes are needed to beat back an attempted filibuster and invoke cloture.

Either way, the numbers are record- breaking for both attempted and successful filibusters. Everyone agrees that the record for cloture motions — 82 set in 1995 and 1996 — likely will be shattered by this summer, if not sooner.

Reid was right that the Senate had voted on cloture 72 times as of Monday afternoon — 73 after the chamber voted on a consumer product safety bill that evening. But on at least five of those votes, it was Democrats, not Republicans, who led the charge against the bill or nominee.

Reid acknowledged that point Tuesday, saying, “Now, in the 72, were there two or three that Democrats caused? Perhaps so. So, if it’ll make everyone feel better, we’ll lower the chart to 69.”

Republicans argue that they supported 37 cloture motions. That means they blocked cloture, or filibustered, a bill or amendment 30 times, though they caution that many of those underlying measures — 11 by Roll Call’s count — eventually passed the Senate.

“A ‘no’ vote on cloture is not necessarily a filibuster,” McConnell spokesman Don Stewart said.

Stewart conceded that Republicans were involved in at least 13 filibusters in which the legislation being blocked died on the vine, but he pointed out that the filibuster on the immigration bill last summer was a bipartisan effort.

Other bills Republicans take credit for killing include a union-organizing bill known as “card check,” the District of Columbia voting rights legislation, a measure to allow Medicare officials to negotiate lower drug prices for beneficiaries and the numerous Democratic attempts to force a drawdown of troops in Iraq.

But Democrats said whether Republicans voted for or against cloture, the minority needlessly is impeding Senate action on otherwise bipartisan bills in an attempt to prevent Democrats from having a robust record of legislative accomplishments come year end.

“That is such a specious argument,” Reid said on Tuesday. “I heard that on the floor yesterday. My counterpart, Sen. McConnell, said, ‘Well, cloture was invoked. There were 86 Senators voting for it.’ Well, we wouldn’t have had the cloture vote if it hadn’t been for them, and we wouldn’t have had to waste 30 hours had it not been for them.”

Once a motion to invoke cloture is filed, Senators have 30 hours to debate it and another 30 hours if the motion is approved.

“If you look at all of the times that they have forced us to waste 30 hours after a cloture vote, we’re talking about weeks upon weeks of legislative limbo where the Senate was doing nothing,” said Reid spokesman Rodell Mollineau.

Additionally, GOP-led filibusters have forced Democrats to scale back some of the bills that eventually passed, even though the original provisions had bipartisan support.

Republicans successfully filibustered both an electricity proposal and an energy tax package in the runup to passage of new fuel economy standards for cars and trucks last year. For example, 59 Senators voted to limit debate on an energy bill that included the energy tax provisions.

Additionally, Democrats fell one vote short of the 60 they needed to adopt a broader economic stimulus package than the House-passed measure. The House stimulus bill, which included tax rebate checks for low- and middle-income tax filers, eventually became law with modest changes by the Senate.

“I think people will have a hard time calling that a filibuster when they get their rebate checks this year,” Stewart said.

In essence, Reid and McConnell’s dispute comes down to the largely behind-the-scenes negotiations between the majority and minority on how to bring a bill to the floor and which amendments, if any, should be offered.

If a unanimous consent agreement can be reached on the number of amendments and on time limits for debate, work on the bill often goes smoothly. But those agreements have been few and far between during the 110th Congress, with McConnell arguing that Reid is trying to limit the minority’s ability to offer amendments and Reid countering that McConnell wants to offer poison pill proposals that would take down the bills.

“The underlying premise here is when they try to move partisan bills, they’re not successful, but when they work with us to make a bipartisan bill, it becomes law,” Stewart said.

He added that Democrats could have saved some of the bills that Republicans take credit for filibustering if they had just reached out to the minority more often.

“I don’t concede the point that it’s the Republicans’ fault that a bill died,” Stewart said.

But Mollineau disputed that: “There’s a fine line between minority rights and obstruction, and this Republican minority crossed that line a long time ago.”