(FORTUNE Magazine) – JESSE HELMS has been a vituperative warrior of the Republican party's right wing since he arrived in the Senate in 1973. Though it doesn't love them, Congress tolerates ideologues -- they ensure that minority views are heard. But Helms has gone further than any Senator since Alabama's filibuster-prone James B. Allen in abusing the Senate's creaky rules and fusty customs. In the process Helms has become an impediment to the foreign policy of his own party's President and a source of confusion and concern for American diplomats and businessmen abroad. So why doesn't somebody rein him in? Blame maybe 25% on those fusty customs and the rest on President Reagan and Republican leaders in the Senate, who have various reasons for giving Helms running room. Helms's direct effect on policy is minimal. An undistinguished chairman of the Agriculture Committee, he has looked out for the tobacco and peanut interests of his native North Carolina and not much else. What excites him is foreign affairs; he serves as the No. 2 Republican on the Foreign Relations Committee. A Baltimore cartoonist's gibe, that Helms never met a right-wing dictator he didn't like, isn't far from the truth. A favorite tactic is the road show. Helms and his staff, a sort of airborne Star Chamber, periodically descend on other countries to protect democracy from what Helms likes to lump together as ''the media, the Marxists, and the U.S. State Department.'' The target in July was Chile. The Reagan Administration, fresh from its successes in helping to unseat dictators in Haiti and the Philippines, has been pushing strong man Augusto Pinochet to speed up Chile's transition to democracy. Helms hit Santiago in a blaze of headlines, proclaiming his approval of Pinochet and suggesting that the U.S. ambassador was being used by the local Communists. Some American businessmen in Chile think Pinochet has got a bum rap in the U.S. media, but they were nevertheless unsettled by Helms's performance. ''It tended to cloud U.S. policy in the eyes of Americans and Chileans as well,'' says the head of a U.S. business group in Santiago. American businessmen in Chile fear that such publicity will harden U.S. opposition to Pinochet, increasing pressure on the Administration to block World Bank loans. The loans are needed, they say, to help stabilize a fragile economic and political situation. Back in Washington Helms tries to influence foreign policy by delaying appointments of ambassadors and promotions of other State Department officials. Sometimes he considers Reagan's choices soft on Communism, sometimes he merely wants a trade-off -- a promise from the White House to appoint one of his hard-right allies to some other government post, for example. Helms takes full advantage of the Senate's tradition of courtesy: A single Senator can ask his party leader to ''hold'' a nomination. This nicety is backed by the threat that a Senator will filibuster to delay confirmation -- and the rest of the Senate's business -- if his wish is ignored. Using that method Helms has delayed dozens of appointments in his Senate career; 19, by his count, since Reagan was elected. When Congress adjourned in August, Helms had been holding two diplomatic promotions hostage for more than three months. Last year he delayed the confirmation of Winston Lord as ambassador to China for several months. Helms has been a critic of U.S. policy toward China since President Nixon first visited Peking, and he wanted assurances that the U.S. would not assist China's population control programs. On a visit to China during the delay, Vice President Bush had to unruffle official feathers. The uncertainty in an ambassadorless country can affect the resident American business community. Says former Senator Charles H. Percy, once the chief executive of Bell & Howell: ''The more our embassies get into commercial matters -- business, trade, and the transfer of technology -- the more the absence of an ambassador is harmful to the national interest.'' Helms's intransigence can cost business plenty. On another front in his one- man war against China, Helms blocked ratification of an important tax treaty that cuts China's taxes on dividend, interest, and royalty income of many U.S. companies from 20% to 10%. The treaty had been in the works since 1982 and was signed by President Reagan in 1984. Helms held up Senate approval until July. The price of the delay for U.S. companies? ''It's safe to say it's in the millions,'' says John Callebaut of the National Council for United States- China Trade. Helms can be harnessed. He justifies his crusades by claiming the State Department's policies are at odds with the President's. The White House could correct that impression. Majority Leader Robert Dole bestows the courtesy that Helms uses to put confirmations on hold. Dole could say no. ''If the Administration resists him, and if his colleagues resist him, then his ability to use the Senate's rules to gain any advantage is limited,'' says Thomas E. Mann, executive director of the American Political Science Association. Reagan, known for an unwavering loyalty to old friends, may be loath to lean too hard: In the 1976 presidential primaries, when most prominent Republicans had written Reagan off, Helms delivered a victory in North Carolina. Dole is a potential candidate for President, and one thing that Republican hopefuls share is an aversion to antagonizing leaders of the right. Even when they're clearly in the wrong.