In the never-ending debate about whether Jon Stewart is a comedian with opinions or an activist who happens to make jokes, he’s always argued for the former. When Tucker Carlson accused Stewart of liberal hackery on Crossfire in 2004, Stewart famously played the joker card. “You’re on CNN,” he said. “The show that leads into me is puppets making crank phone calls.”

It’s true—Stewart leans left, but the jokes always come first. At October’s Rally To Restore Sanity, which many observers considered his coming-out party as the anti-Glenn Beck, Stewart was careful not to cross the line into advocacy. He didn’t even tell people to vote. He’s just not “in the game,” he told Rachel Maddow in an interview in November. “I’m in the stands yelling things, criticizing.”

Last week, Stewart stepped onto the field. The change came after Senate Republicans blocked a bill that would provide $7.4 billion in medical benefits to firefighters, police officers, and health workers who got sick from working at Ground Zero on and after 9/11. Stewart didn’t just mock the 42 Republicans who refused to consider the bill until the Bush tax cuts were extended. He ripped them apart. “I can’t wait for them to take to the floor to talk about why their party hates first responders,” he said. He shredded Sen. Mike Enzi’s argument that the bill would lead to waste, fraud, and abuse by pointing to Enzi’s support for corruption-riddled spending in Iraq. Last week, he did a follow-up segment, “Worst Responders,” in which he called the refusal to pass the 9/11 bill “an outrageous abdication of our responsibility to those who were most heroic on 9/11.” The bill would even be paid for by closing corporate tax loopholes. “It’s a win-win-win-win-just [bleep] do it!” he yelled. He also blasted the media for failing to cover the story, noting that the only cable news network to devote a full segment to the issue was Al Jazeera. He then interviewed four first responders—a fireman, a police officer, a Department of Transportation worker, and an engineer—who suffered illnesses as a result of their work at Ground Zero. The segment had funny moments. But the jokes didn’t come first.

And it worked. After Stewart’s tirade, other networks started to cover the story. On Fox News, Shepard Smith called the Republican obstruction “shameful.” ABC News noted that Democrats haven’t exactly been pushing hard to pass the legislation. Rachel Maddow ran a long Daily Show clip and praised Stewart for doing a “great service.” Now, with the hours ticking away before winter recess, Congress seems poised to pass a bill, with its top boosters, New York Sens. Charles Schumer and Kirsten Gillibrand, announcing that “the finish line … is in sight.”

So let me get this straight. Jon Stewart is “just a comedian,” yet he managed to single-handedly fast-track a left-for-dead bill through the U.S. Congress in a matter of days? Not quite. The bill wasn’t as far from passage as it seemed—Stewart just shined a light on the issue at the right moment. In early December, Republicans blocked the bill because of the tax deal. After the tax package passed on Friday, Dec. 17, Democrats were finally able to discuss the 9/11 bill with the GOP. Republicans didn’t object to giving benefits to 9/11 workers, they said. They just didn’t like the way it was paid for. So senators rejiggered the payment mechanisms—it would have been covered by closing a corporate tax loophole; now it will be paid for mainly with a 2 percent fee on federal contracts awarded to foreign countries that don’t allow U.S. businesses to compete—and brought the cost of the bill down from $7.4 billion to $6.2 billion, after which Republicans were more willing to get onboard.

John Feal, founder of the FealGood Foundation who connected Stewart with the first responders who came on the show, says moving the bill toward passage has been a team effort. But he credits Stewart for its recent progress: “What Jon Stewart did was he literally shamed conventional media and the U.S. government into doing the right thing.”

Stewart would probably argue that pushing for 9/11 workers comp—9/11 workers comp, for Chrissake!—isn’t taking a political stance. It’s taking a stance for decency, heroism, and the American people. Indeed, he called it “the Least-We-Can-Do-No-Brainer Act of 2010.” But stripped of the funny, that sounds a lot like what a politician would say. So did Stewart’s cheap shot about Mitch McConnell crying over the departure of his friend Sen. Judd Gregg—but not, Stewart seemed to suggest, about 9/11. Republicans may have had a flimsy case for blocking the bill, and Stewart rightly mocked the GOP for failing to help 9/11 workers after milking the tragedy all these years, but by shaming them in the name of 9/11 workers, he was engaging in demagoguery himself. It may have been for a good cause, but it was political demagoguery all the same.

Stewart has shown ambivalence about whether to insert himself into the political arena. When Rachel Maddow argued in an interview with Stewart last month that they both had political agendas, Stewart disagreed. The difference, he told Maddow, is that “You’re in the game.” Stewart said that at the Rally to Restore Sanity,

I could have gotten on the field. And people got mad that I didn’t. But that was the point. … The next thing I could do is step onto the field and go, So now,here’s what we’re gonna do. … But I don’t. That’s my failing. And my indulgence. But I feel like I am where I belong. … I don’t take any satisfaction in that. And I don’t take any satisfaction in just being a critic. Roger Ebert doesn’t make movies. So to say, Well, Roger, you’re in the game, well, no he’s not. He’s not making movies. He’s sitting in his seat saying, This movie sucks. That’s me.

Presumably Stewart saw the 9/11 health-benefits bill as a test. He could either keep standing on the sidelines, tossing empty beer cans. Or he could suit up. He chose to suit up. The question now is whether he’ll pretend it was a clown suit all along.

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