IN A DEMOCRACY, standards of civil discourse are as important as they are indefinable. Yet wherever one draws the line, Rush Limbaugh’s vile rants against Georgetown University law student Sandra Fluke crossed it. Mr. Limbaugh is angry at President Obama’s efforts to require the provision of contraception under employer-paid health insurance and the White House’s attempts to make some political hay out of the policy. His way of showing this anger was to smear Ms. Fluke, who approached Congress to support the plan, as a “slut” seeking a government subsidy for her promiscuity.

Like other “shock jocks,” Mr. Limbaugh has committed verbal excesses in the past. But in its wanton vulgarity and cruelty, this episode stands out. Mr. Limbaugh’s audience, and those in politics who seek his favor as a means of reaching that audience, need to take special note.

We are not calling for censorship. Nor are we suggesting that the ostensible policy issue here — mandatory provision of contraception under health insurance paid for by religious-based institutions such as Georgetown — is a simple one. Those who questioned President Obama’s initial decisions in this area — we among them — were not waging a “war on women,” as Democrats have alleged in strident fundraising appeals.

What we are saying is that Mr. Limbaugh has abused his unique position within the conservative media to smear and vilify a citizen engaged in the exercise of her First Amendment rights, and in the process he debased a national political discourse that needs no further debasing. This is not the way a decent citizen behaves, much less a citizen who wields significant de facto power in a major political party. While Republican leaders owe no apology for Mr. Limbaugh’s comments, they do have a responsibility to repudiate them — and him.

House Speaker John Boehner took a step in that direction Friday: “The speaker obviously believes the use of those words was inappropriate, as is trying to raise money off the situation,” Boehner spokesman Michael Steel said in an e-mail Friday morning. But there’s no moral equivalency between the Democrats’ hyperbolic but abstract “war on women” line and Mr. Limbaugh’s targeted attack. Mr. Boehner and others of his stature need to say unequivocally that such gutter rhetoric has no place in their party or in American politics.

Incivility is not a one-way street in America. Far from it: Mr. Limbaugh’s left-wing equivalents have trashed any number of conservatives over the years. Conservatives have a point when they protest that the “mainstream media” don’t always heed their legitimate grievances.

Yet under the influence of Mr. Limbaugh and his ilk, the Republicans risk coming before the voters in 2012, and after, with nothing but grievances. This is what former Florida governor Jeb Bush was trying to tell his fellow Republicans when he observed, apropos of a recent discourse in the GOP primary: “It’s a little troubling sometimes when people are appealing to people’s fears and emotion rather than trying to get them to look over the horizon for a broader perspective, and that’s kind of where we are.”

For the good of U.S. political culture — or at least its own political self-interest — the GOP must distance itself from Mr. Limbaugh. In response to listener complaints and, apparently, the promptings of its own corporate conscience, Sleep Train Mattress Centers has quit advertising on Mr. Limbaugh’s show. Dare Republican leaders show less decency?