Senate Democrats spent Thursday night hammering away at Sen. Jim Bunning (R-Ky.) for single-handedly holding up action in the upper chamber but he blurted out a message to one of them on the Senate floor: Tough st.

In an unusual display in the normally sleepy chamber, Bunning without the support of GOP leadership has blocked efforts to quickly approve a series of extensions to measures that would otherwise expire Sunday, including unemployment insurance and the Cobra program that allows people who lose their health benefits to continue getting coverage.

And that has led to a furious exchange on the floor, with Democrats attacking the senator, who has refused to relent on his objection, in unusually harsh terms.

In a colloquy with Senate Majority Whip Dick Durbin (D-Ill.), Sen. Jeff Merkley, a freshman Democrat from Oregon, was pleading for Bunning to drop his objection, when the Kentucky Republican got fed up.

Tough st, Bunning said as he was seated in the back row, overheard by the floor staff and others in attendance.

A spokesman for Bunning did not immediately respond to a request for comment.

Its rare for senators to curse at one another on the floor of the chamber. In 2004, Dick Cheney famously told Sen. Patrick Leahy to f- yourself when the vice president appeared for a photo session in the upper chamber.

Bunning is furious about increased spending in the Senate but hes waging a lonely battle to stop it. The senior senator from his state, Republican Leader Mitch McConnell, with whom he has a frosty relationship, is not backing him up. If he refuses to relent, Democrats will have to file cloture to shut down debate, pushing back final action until next week.

But Democrats are eager to have this fight; even though they know that Bunning remains largely by himself, they know that hammering away at the Kentucky Republican will drill home their argument that the GOP is out to obstruct progress.

On the floor, Bunning leaned back in his chair, legs crossed, as he listened to a slew of Democratic senators talk about the bill he is blocking.

Senate Majority Leader Harry Reid (D-Nev.) approached Bunning around 9:30 p.m., and they spoke for a moment before Reid left the floor.

Reid has asked for unanimous consent to approve the package of provisions that expire Sunday, which also include 30-day extensions of flood insurance, highway funding and small business loans. But Bunning continues to object to the unanimous consent requests.

To maximize pressure on Bunning, Durbin has been reading messages from Kentucky residents and unemployment statistics from counties around the state, whose unemployment rate stands at 10.7 percent, above the national average. One country, Magoffin County, has 21.4 percent of its residents unemployed, Durbin said. Merkley said he is deeply disturbed that Bunning can be is so disconnected from the challenges of working Americans.