Are we being fair to Rush Limbaugh?

Radio talk show host Rush Limbaugh is under fire for his remarks about a Georgetown University law student. David Frum: Limbaugh's backers assert liberal talkers also guilty of outrageous statements He says the hunt for equally offensive comments is a waste of time Frum: No one on the left holds the power broker position Rush Limbaugh has on the right Even by the standards of radio talk, Limbaugh's tirade was a new low, Frum says

Editor's note: David Frum, a CNN contributor, is a contributing editor at Newsweek and The Daily Beast. He was a special assistant to President George W. Bush from 2001 to 2002 and is the author of six books, including "Comeback: Conservatism That Can Win Again."

(CNN) -- "It's not fair!"

As advertisers quit the Rush Limbaugh radio program -- and as Republican politicians squirm uncomfortably -- the broadcaster's fans are complaining about double standards.

Yes, they'll concede, maybe Limbaugh went too far in denouncing a female law student as a "slut" and a "prostitute" and then demanding that she post a sex tape online for him to view.

But look (they continue) at all the liberal/lefty broadcasters who have also said obnoxious things! No one calls Democratic politicians to account for them. Why us?

It's a question that will be aired often in the week ahead. Here's the answer, in four points.

Point 1: Even by the rough standards of cable/talk radio/digital talk, Limbaugh's verbal abuse of Sandra Fluke set a new kind of low. I can't recall anything as brutal, ugly and deliberate ever being said by such a prominent person and so emphatically repeated. This was not a case of a bad "word choice." It was a brutally sexualized accusation, against a specific person, prolonged over three days.

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Point 2: The cases that conservatives cite as somehow equivalent to Limbaugh's tirade against Fluke by and large did bring consequences for their authors.

After David Letterman for example made an ugly joke about Sarah Palin's daughter, he delivered an abject seven-minute apology on air. (To which Palin responded by refusing the apology and insinuating that David Letterman was a child molester.)

When liberal talker Ed Schultz nastily called my dear friend Laura Ingraham a "slut" on his radio show, MSNBC responded by suspending Schultz for a week without pay from his TV show. Schultz likewise apologized in person on air. (Ingraham accepted the apology with grace and humor.)

The exception to the general rule is Bill Maher, who never apologized for calling Palin by a demeaning sexual epithet. But now see point 3:

Point 3: Limbaugh's place in American public life is in no way comparable to that of David Letterman, Bill Maher or Ed Schultz.

Letterman is not a political figure at all; and while Maher and Schultz strongly identify as liberals, neither qualifies as anything like a powerbroker in the Democratic Party. I'm sure the Barack Obama re-election effort is happy to have Maher's million-dollar gift, but I sincerely doubt there is a Democratic congressman who worries much whether Maher criticizes him. A word of criticism from Limbaugh, by contrast, will reduce almost any member of the Republican caucus to abject groveling. See, for example: GINGERY, PHIL.

I can't recall anything as brutal, ugly, and deliberate ever being said by such a prominent person and so emphatically repeated. David Frum

Among TV and radio talkers and entertainers, there is none who commands anything like the deference that Limbaugh commands from Republicans: not Rachel Maddow, not Jon Stewart, not Michael Moore, not Keith Olbermann at his zenith. Democratic politicians may wish for favorable comment from their talkers, but they are not terrified of negative comment from them in the way that Republican politicians live in fear of a negative word from Limbaugh.

The ultimate test came in 2002, the vote to authorize force against Iraq. Almost every liberal talker opposed that vote. Hillary Clinton, with her eye on a presidential run in 2008, voted in favor.

That is why no one asks Democratic politicians to repudiate the latest strident statement from an Olbermann or a Moore. There's no sport in it. It's too easy for them to say, "Sure." For Republicans, it's tough.

But maybe, after this latest outburst, a little less tough?

Point 4: Most fundamentally, why the impulse to counter one outrageous stunt by rummaging through the archives in search of some supposedly offsetting outrageous stunt? Why not respond to an indecent act on its own terms, and then -- if there's another indecency later -- react to that too, and on its own terms?

Instead, public life is reduced to a revenge drama. Each offense is condoned by reference to some previous offense by some undefined "them" who supposedly once did something even worse, or anyway nearly as bad, at some point in the past.

But this latest Limbaugh outburst is so "piggish," to borrow a word from Peggy Noonan, as to overwhelm the revenge drama. (On Saturday, Limbaugh apologized "for the insulting word choices.")

It is the bottom of the barrel of shock talk.

And the good news is that from the bottom of the barrel, there is nowhere to go but up.

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The opinions expressed in this commentary are solely those of David Frum.