Stephen Colbert is no Elmo — which is why it was crazy for House Democrats to have him testify before a subcommittee last week about migrant labour.

Speaker Nancy Pelosi proclaimed it "great" that a celebrity such as Colbert "can bring attention to an important issue like immigration." Majority Leader Steny Hoyer had it only half right when he described Colbert's appearance as "an embarrassment." The wrong part was deeming the episode embarrassing "for Mr. Colbert more than the House."

He wishes. Mr. Leader — have you watched his show? To be Stephen Colbert is to be immune from embarrassment.

I don't want to come across as humourless here; I'm a huge Colbert fan. And I'm not naive about the elevated state of congressional proceedings; hence the Elmo reference. The adorable Muppet testified in furry red splendor about the importance of musical education back in 2002, when Republicans were in charge.

In an age when celebrity rules, Congress can't be expected to resist the allure. It's too late in the game to get all sniffy about "expert" testimony from celebrities: Angelina Jolie on refugees, Bono on AIDS, Loretta Swit on "crush videos."

So if celebrities want to harness their fame for good, and if lawmakers want to get in on the act, that's fine. I have no problem if Lady Gaga and Harry Reid, on don't ask, don't tell — or Snooki and John McCain on the tanning tax — are Twitter pals.

But Colbert's testimony was not history repeating itself as farce — it was history starting as farce. That's to be expected when lawmakers appear, at their own risk, on "The Colbert Report." But there is a difference between lawmakers electing to be a prop in Colbert's show and letting Colbert turn their show into his prop.

And that's what happened before the House Judiciary Committee's immigration subcommittee. The panel's chair, California Democrat Zoe Lofgren, invited Colbert to appear after they spent a day picking vegetables at a New York farm as part of the United Farm Workers' "Take Our Jobs" campaign.

Judiciary Chairman John Conyers tried to save Lofgren from her stunt. "I would like to recommend that, now that we've got all this attention, that you excuse yourself," he told Colbert.

The comedian said he'd be glad to comply, but the gentle-lady from California wasn't about to bid goodbye to all those cameras — the most, she noted, since perhaps the Clinton impeachment proceedings.

And so Colbert proceeded, in full faux bombastic mode. He expressed "hope that my star power can bump this hearing all the way up to C-SPAN I." He asked to "submit a video of my colonoscopy into the congressional record." He argued that "my great-grandfather did not travel across 4,000 miles of the Atlantic Ocean to see this country overrun by immigrants."

Ba-dum-bum. All in the first minute-and-a-half.

Lofgren, when I spoke with her on Tuesday, expressed no regrets. "Outside the Beltway, people are thinking a point was made, and I think the understanding of farmworker issues has increased dramatically as a result," she said.

Indeed, there were moments, affecting ones, when Colbert stepped out of character. "It just seems like one of the least powerful people in the United States are migrant workers who come and do our work but don't have any rights as a result," he said.

But there were more moments when the hearing was a platform for Colbert to jab his hosts. "Maybe this ag jobs bill would help," he suggested at one point. "I don't know. Like most members of Congress, I haven't read it." Concluding his remarks, Colbert said, "I trust that, following my testimony, both sides will work together on this issue in the best interests of the American people as you always do."

At this point, the audience laughed.

This isn't the most embarrassing spectacle to unfold before Congress. (I was at the Anita Hill hearings, so I know firsthand.) Nor is it the biggest story around. But it is emblematic of the dumbing down of American political culture — more circuses, less bread.

Colbert and Jon Stewart have more than enough material to lampoon politicians without Congress inviting them over for more. As usual, Stewart said it best, in his show Monday night. "Of course Colbert is more embarrassed than the House of Representatives," he said. "Colbert still has dignity and integrity left to lose."

How smart of the subcommittee to offer a reminder.

Ruth Marcus' e-mail address is ruthmarcus(at symbol)washpost.com.

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