Mr. Grayson could be the latest incarnation of what in the American political idiom is known as a wing nut — a loud darling of cable television and talk radio whose remarks are outrageous but often serious enough not to be dismissed entirely. Mr. Grayson is the more notable because he hurls his nuts from the left in a winger world long associated with the right.

That might just be the point. House Democratic leaders publicly frown on his behavior and have urged him to tone it down, saying he contributes to an atmosphere of incivility. But the incivility is no accident; nor is the bluster. Such antics are often quickly rewarded in the media-crazed wrestling pit of American politics. One talked-about TV appearance leads to three more; every quotable outburst is a potential pitch, spread instantly by YouTube and blogs to an eager audience that can cheer by way of campaign donations made with the click of a mouse.

Some Democrats also say that Mr. Grayson fills a void, defying their party’s inferiority complex, the constant sense that liberals just are not tough enough…

“You cringe,” said Representative Earl Blumenauer, Democrat of Oregon and an unabashed liberal but also a buttoned-down gentleman. “We’re at risk of having a self-reinforcing corrosive process that drives reasonable people away.” He added: “It breaks my heart.”