A win, a loss for GOP senators highlight role of conservatives.

Perhaps the bitterest, most extravagant, and certainly the most publicized race for the United States Senate ended with New Right champion Jesse Helms returning to Washington.

The North Carolina campaign pitted the national far-right movement against a national coalition of moderates and liberals. From coast to coast, contributors sent money to both sides in a battle that will probably cost $26 million by the time the bills are added up.

It was a major victory for the New Right, as GOP Senator Helms defeated moderate Democratic Gov. James B. Hunt Jr. The senator is easily the most visible leader of the New Right. Since his arrival in Congress in 1973, he has led the fight against abortion and championed issues ranging from school prayer to a ban on busing for school desegregation.

An activist on foreign affairs, he has befriended right-wing leaders worldwide. He has held up State Department nominations when he found the nominee not conservative enough.

''I think it says that the New Right is alive and well, because the liberals threw everything they had at Jesse Helms,'' says Paul Weyrich, a New Right and anti-abortion leader who heads the Committee for the Survival of a Free Congress. ''I think it suggests that Jesse Helms has a strong constituency not only in North Carolina but across the country.''

In fact, Republican Helms won by only 2 percentage points, though his state gave President Reagan a 22 percent margin. This points to a coattail effect.

Helms was also aided by a dramatic increase in North Carolina of a half-million new voters, spurred largely by the New Right religious group, Moral Majority, and by President Reagan's popularity.

But the Helms victory margin lay more in the foothills of North Carolina than in the national campaign. A little more than a year ago, Helms was 30 points behind his challenger. By election day, he had solidified for the third time a base of white voters in this massively Democratic state.

In what is widely viewed as his most successful campaign move, Helms launched a one-man filibuster in the Senate against a national holiday for slain civil rights leader Martin Luther King Jr. Although the crusade failed, it helped him among whites.

''That was where he recaptured his white majority,'' says Merle Black, a political scientist at the University of North Carolina. ''He did the equivalent of George Wallace standing in the schoolhouse door.''

That act imprinted on the public an image of Helms as a man who ''stands for what he believes,'' an attribute that voters repeatedly mentioned to this reporter before the election. Meanwhile, with the aid of almost unlimited funding, Helms launched an attack on his opponent as a slick politician without firm principles.

''It's not true,'' says Hunt press secretary Will Marshall of the charge, but ''it was frustrating to combat.''

However, the Hunt camp is clearly signaling that although the battle is lost, the war is not over. ''This was a national campaign, and Jim Hunt is now known nationally,'' says Mr. Marshall. Pointing to North Carolina as home base for Helms's New Right, he suggested that Hunt may use his national network of contributors to build a counter group. Helms (R) 1,153,342 51.7% Hunt (D) 1,066,581 47.8%