If you have committed a sexual indiscretion, do not plan to run for president in the year 2000.

That, finally, is something on which defenders of President Clinton and his critics wholeheartedly agree.Presidential attack dog James Carville, who has made a career lately out of excoriating independent counsel Kenneth Starr for investigating Clinton, told reporters the other day that anybody with a potential sex scandal in his or her past will be politically dead in the water.

As a political consultant, even one who has engineered come-from-behind squeaker victories, he is convinced that in the presidential race in 2000, candidates with any sexual improprieties in their past will find such embarrassments public knowledge.

"In the year 2000 everybody's sex life is fair game . . . Everybody is going down this road gleefully. The press will use a lofty rationale but say, " `We have to do this,' " Carville said.

A "test of sexual purity for national office," Carville said contemptuously, will be Starr's biggest legacy.

Starr insists he is not investigating the president's sex life but whether Clinton lied when he denied a sexual relationship with Monica Lewinsky and that he encouraged her to lie about it under oath to lawyers in Paula Jones' sexual harassment case against him.

But in trying to find out if Clinton lied, Starr, of course, has to ascertain if there was sex.

As Clinton continues to say nothing about the nature of his relationship with the former White House intern, on the grounds that his lawyers are worried about Starr's power, he permits the country to engage in an orgy of bad jokes, gross jokes and gossip that is diminishing the presidency.

William Bennett, the conservative standard bearer of virtue (whose brother Bob ironically represents the president for $475 an hour in the Jones lawsuit), agrees that for now adultery is reason not to run for public office.

He said he has counseled several Republicans against running because of sexual indiscretions. "I told them they'd never get the nomination," he said.

Bennett, who believes there will be an impeachment hearing against Clinton in the House later this year, argues forcefully that Clinton is guilty of having sex in or near the Oval Office with a then-21-year-old White House intern despite his flat denial to the nation. Bennett scoffs at Clinton's denial, saying that if nothing improper happened, Clinton would be out talking about it "and embarrassing me by proving it's not true."

Bennett says he's trying to lobby Democrats to go to Clinton and urge him to explain to the American people what happened between Lewinsky and him. But Bennett already has made up his mind: Clinton did it, lied and should resign.

And he charges Clinton with immature behavior, arguing that Clinton implicitly promised the nation he'd refrain from sexual misconduct after Gennifer Flower alleged a sexual relationship with him while he was governor of Arkansas.

For his part, Carville says that he has not asked Clinton personally whether he had a sexual relationship with Lewinsky because he takes him at his word, made in public, that he did not. Carville does not dwell on that but on his allegation that Starr, a Republican, is biased against Clinton and is "out to get him." He says Clinton agrees.

The press, Bennett and Carville both agree, is now all but duty-bound to pursue allegations of sexual misconduct in presidential candidates on grounds it's an indicator of character and, given recent history, might be used as a way to blackmail a future pres-i-dent.

Bennett and Carville agree that sex as a moral litmus test might not continue to be all-important after the 2000 race (after all, voters in 1992 and 1996 elected Clinton despite the allegations of adultery). But they agree such scrutiny is unavoidable through the next race.

To those who say a person's sex life is private, this magnifying glass on privacy won't seem fair; to others, it will be welcomed as a kind of antidote to years of an increasingly voracious national appetite for titillation.