Washington DC - Jon Stewart blasted Senate Republicans as "cowards" and "motherf***ers" after they blocked the passage of a bill aimed at providing healthcare for veterans suffering from the effects of toxic burn pits in war zones.

In a move that sparked an outpouring of outrage and disgust, almost all GOP Senators voted to filibuster the PACT Act, which would have expanded healthcare to millions of vets that are living with medical conditions caused by the toxic smoke from burn pits used in Afghanistan and Iraq.

There were also provisions for veterans of the Vietnam war exposed to the deadly Agent Orange.

Speaking in front of the Capitol building alongside other activists, Stewart didn't hold back: "Ain't this a b***. America's heroes, who fought in our wars, are outside sweating their a**es off with oxygen, battling all kinds of ailments, while these motherf***ers sit in the air conditioning, walled off from any of it."

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Torching Senate Minority Leader Mitch McConnell for "flipping" on the issue, the former Daily Show host added: "The Senate is where accountability goes to die. These people don’t care. They’re never losing their jobs, they’re never losing their healthcare."

"I’m used to the lies, I’m used to the hypocrisy… I’m used to all of it, but I am not used to the cruelty."

One of the main targets of Stewart's wrath was Pennsylvania Senator Pat Toomey, who led the effort to block the bill.

Despite having voting overwhelmingly in favor of the PACT Act in June, he and dozens of other Republicans changed tack the second time around, taking advantage of a small technical issue which meant the legislation had to be voted through again.

Toomey and his colleagues somehow found "unrelated spending" in the bill, despite not being able to point out anything specific, and accused Democrats of piling the funds into an unregulated "slush fund."

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"The question is..How do you shame the shameless?" Stewart tweeted, tagging Toomey and McConnell before adding, "or really..how do you shame the shameful?"

The comedian has spent the better part of two decades advocating for veterans and 9/11 first responders.