In a manner reminiscent of the spirit of McCarthyism, a small band of archconservatives in the Senate is waging a dirty little war. This time it is against the career people in the Department of State's Foreign Service and the man who is supposed to be in charge, Secretary George Shultz.

I say "supposed to be" because that's what the war is all about. On the face of it, it turns on particular presidential nominations, most conspicuously that of Rozanne Ridgway. She is a highly respected career officer whom Shultz wants as his assistant secretary of state for European affairs. Her credentials are impeccable. But the conservative challenge has nothing to do with professionalism. It has to do with ideology and with who should be making these personnel decisions on behalf of the president.

Shultz has this presumptuous notion (as the right-wing Senate ideologues see it) that he ought to be able, subject to senatorial "advice and consent," to surround himself with trusted, tested, top-level advisers of his own choosing. He also thinks he has the right (subject to the same constitutional restraints) to select the career officers he thinks will ably and faithfully act in the interest of Ronald Reagan's policies.

That's not only his sense of how it ought to work; it's also his sense of how the president thinks it ought to work.

Not so Sen. Jesse Helms. Having made a shambles of former Secretary of State Alexander Haig's efforts to staff the foreign policy apparat at the start of the first Reagan term, Helms and more than a dozen others are doing their obstructionist best to make life at least as miserable for the man Ronald Reagan has entrusted with the role of principal foreign policy- maker in the second Reagan term.

Helms and five hard-right colleagues recently wrote Shultz a letter demanding that the secretary consult with them before he even makes his selections. That way, the senatorial SWAT team could hope to knock off the nominations of all but the truest conservative believers by threats of filibusters or other harassment, without ever getting to an open confirmation process and a vote by the full Senate. Shultz politely replied that the constitutional provision for "advice and consent" was consultation enough.

So now we have the familiar techniques and tactics: the blacklisting of professionals; guilt by association (not with communists, mind you -- association with Democrats is enough); loyalty tests graded by devotion to pure Reaganism (simple patriotism or even Republican Party affiliation doesn't do it).

The breakage is familiar, as well: damage to distinguished careers, for example, or to morale in the professional diplomatic corps. The politicians and the political appointees come and go, but the Foreign Service's expertise and its contribution to continuity and to institutional memory are indispensable.

Finally, there's the damage to the orderly workings of the foreign policy machinery. Even when Helms loses, which he usually does in the end, the disruption and delay constitute a considerable distraction from serious business.

Helms and his unhappy band have marked down a half-dozen recent Shultz nominees as insufficiently antediluvian to fit the Helms world view. But the Ridgway case is as good an example as any of how this political terrorism works. Mostly it takes the form of downright disingenuous assaults on the qualifications and the integrity of individual nominees, by word of mouth and by friendly media mouthpieces.

The whispering campaign would have it that Ridgway is unqualified to handle European affairs by reason of having no arms control background, a requirement never before imposed on the job. It was not required of the incumbent chief arms control negotiator, Max Kampelman. She has no experience with the Soviets, it is said, as if her latest tour as ambassador to communist East Germany, a previous ambassadorship in Finland and earlier work on NATO affairs had offered no insights on the "evil empire."

But didn't her career fetch her up for a few months in the job of counselor at State while (hang on!) Jimmy Carter was president? Indeed it did. That may be the real right-wing knock against Ridgway. But the implication of partisan taint goes against a tradition of awarding that post most often to the cream of the career crop.

Finally, Helms and Co. are even circulating the nonsense that Shultz is "purging" the ranks of the political appointees by putting a "21/2-year" limit on their tours, by way of favoring the professionals. Actually, the president recently signed off on a general three-year rule on political appointees, bringing them in line with the same rule for career people laid down early last year.

The insinuation is that career officers can't be trusted to carry out the president's wishes, that the secretary of state can't be trusted to see that they do, and that the president can't be trusted to keep the conservative faith. Against that squalid line of argument, to his lasting credit, George Shultz is hanging tough.