I HAVE A CONFESSION. I am one of those who thinks that Sen. Paul Sarbanes, the Maryland Democrat, is a swell senator. I think he is smart, principled, gutsy a hard worker, and, by golly, a liberal. I wish he felt as strongly about himself as I do.

Instead, he and some other liberals seem to subscribe to the view of the National Conservative Political Action Committee that there is something wrong about being a liberal, about having a body of beliefs and voting accordingly, even if that means voting against simple-minded tax cuts, like Kemp-Roth.

At the moment, Sarbanes and some others are screaming foul because they have been targeted by NCPAC and some other political action groups for what the CIA used to call "termination with extreme prejudice." In political terms, NCPAC would llike Sarbanes dead, which is the way they would like to leave Sen. Edward M. Kennedy and several members of the House. These Democratic liberals have been selected to be examples to others.

But it seems that liberals have already gotten the message. NCPAC has been credited with the 1980 defeats of Sens. George McGovern, Frank Church and John Culver, all Democrats, all liberals and now all into another line of work. Whether NCPAC can take credit for this is a matter of dispute. There was a conservative tide running in the country and these men were demonstrably not conservatives.

At any rate, there is no stopping NCPAC from taking credit for these losses if only because there seems to be no stopping NCPAC from doing anything it wants. Like other political action groups, it is a power unto itself, and while it now toils for a better and purer Grand Old Party, it is not subservient to the GOP. Indeed, the party chairman, Richard Richards, would far prefer it if only NCPAC would follow orders. It will not.

And it will not play fair, either. Its Sarbanes ads are models of political sleaziness. It plays fast and loose with the truth, portraying Sarbanes as a whopper of a senatorial spender who is in favor, for some reason, of just spending money. NCPAC says that Sarbanes has voted "against personal tax reductions, business tax reductions and agaisnt adjusting taxes for inflation." It calls Sarbanes "the biggest spender in Congress," which is, when you come to think of it, a pretty ridiculous statement. There is, in fact, no way to measure these things.

But on only a single substantive issue was NCPAC wrong. It said that Sarbanes has voted for a congressional pay raise and he had not -- at least not recently. On all the other issues, NCPAC is doing nothing more than honoring the American political tradition of fuzzying up the numbers, smearing, insinuating and putting your opponent on the defensive -- pinning a label on him and forcing him to prove it isn't warranted. NCPAC is not the first political organization to do this and neither is it the first independent political group to make a senatorial race its own business. The unions have done this for some time. So has the Americans for Democratic Action and so has Stuart Mott.

In fact, NCPAC has really done nothing more than paint Sarbanes as a liberal. It has put a spotlight on him and instead of his standing up and saying, darn right, he has cried foul. He and other Democrats have complained about NCPAC starting the campaign 18 months before the election and have raised the red herring of out-of-state money. They have quibbled with the words and the numbers instead meeting the challenge head on.

Paul Sarbanes, after all, really is a liberal. He is rated 83 by the ADA, 95 by the Afl-cio. [Barry Goldwater's ratings, by comparison, are 0 and 18.] Being a liberal used to be a statement of fact. Now, it seems to be an accusation. Not only Sarbanes, but most of American liberalism is hiding under a rock. It ought to come out and fight. We would like to hear from the other side.

In Sarbanes' case, there is plenty to hear about. He was a remarkably effective congressman during the Watergate hearings and he has done nothing since then to soil his reputation. He was one of the few in the Senate to anticipate that Alexander Haig would be the debacle at State that he has turned out to be, and he has at least remembered that the best government is not necessarily the one that governs least, but the one that is most equitable. That makes him a liberal. It used to be nothing to be ashamed of.

It still isn't.

NOTE: On Thursday, I wrote that a vitamin company had failed to renew its contract with Billie Jean King in the wake of her admitting that she had had a homosexual affair. The drug company says that the decision not to renew the contract was made months ago and had nothing to do with King's disclosure. It was incorrectly reported by a wire service and I regret the error.