IT'S UNDERSTANDABLE that Republicans in the Senate have enjoyed watching President Clinton and the Democrats squirm on the matter of the Comprehensive Test Ban Treaty. As long as the treaty was languishing, Democrats were pleased to use it as a political club, lambasting the Republicans for not scheduling a ratification vote. But when Majority Leader Trent Lott called the Democrats' bluff and agreed to take up the treaty, it turned out Mr. Clinton didn't have the votes. Treaty opponents had been doing their homework, while the White House had done little advocacy in the Senate or with the public. Now the Democrats piously urge the Republicans not to play political games with the treaty; we need more time, they say.

So the Republicans have had some fun. But the treaty is too important for its fate to be sealed in gotcha politics. A ban on nuclear testing has been a goal of this nation since Republican President Dwight Eisenhower proposed it some four decades ago. To abandon that vision now would be a momentous step, and in our view a mistaken one.

That isn't to say that treaty opponents make no serious arguments. They can make a compelling case, and their ranks include serious thinkers with long experience in defense and foreign policy -- people who can't be lightly dismissed. Nor is it persuasive when treaty supporters argue for ratification because 80 percent or more of the American public supports a test ban. If opponents are bucking public opinion in the interests of what they deem national security, they deserve credit for that, not criticism.

The case has to be won rather on the merits. Opponents make two basic claims: that without testing, the United States cannot be sure of the reliability of its own nuclear arsenals; and that the treaty will not prevent other nations from developing or improving arsenals of their own. Against the first contention, many scientists with great expertise in nuclear weapons testing insist that reliability now can be reasonably guaranteed through computer simulation and other means short of actually setting off a bomb. Sen. Jon Kyl argued on these pages Saturday that U.S. nuclear weapons no longer will deter adversaries who are uncertain those weapons will work. But surely the balance tips the other way; no adversary is going to dare the Air Force to fling a few hundred ICBMs its way because one or two of those warheads might turn out to be duds.

If the treaty doesn't harm U.S. national security, then the second argument against it weakens too. The question becomes not whether a test ban provides absolute guarantees against new nuclear powers emerging but whether it makes such an outcome less likely. It's true that a test ban treaty won't automatically disarm North Korea or other would-be nuclear powers, and it may be true that some cheating can occur. But a treaty will make testing by other countries more difficult and less likely. U.S. ratification would make it easier to work against the spread of nuclear weapons. And a defeat of the treaty in the Senate would fatally weaken American's standing to persuade other nations not to go nuclear. That is a risk the Senate should not take.