Why it is time to stop aiding the rebels. On the eve of the contra aid vote ...

LET'S be very clear about what this week's vote in Congress on further aid to the contras is all about - and what it is not about. In the broadest sense, the vote on President Reagan's latest aid request is about the quality of our nation's involvement in Central America. It is about the values and traditions the United States will uphold in dealing with its neighbors in this hemisphere.

Will this latest - and perhaps last - decision on contra aid reflect the greatness and grandeur of our nation and the political ideals on which it was founded? Will it earn the US the respect of its democratic allies around the world?

Or will it end all prospects of a political resolution of the armed conflict in Nicaragua, sound the death knell to the Guatemala accord, and prolong US involvement as the bankers of a proxy war in that troubled region?

I have no doubt that a vote endorsing the current policy of arming and directing the Nicaraguan resistance is a vote that commits the American people to a policy of more killing and destruction - something a vast majority do not support. It commits us to a policy in neither the national-security interest nor the foreign-policy interest of the United States.

Now, what this week's vote is not about: It is not about surrendering to communism. It is not about reneging on a moral obligation to the Nicaraguan resistance forces not to leave them high and dry. The President, or at least his aides, know full well that provisions of the Guatemala accord permit us to make good on our moral obligation to the contras - an obligation to feed and clothe them while they are being relocated and resettled or, if they choose, reintegrated into the political life of Nicaragua.

For the first time in the seven years since the contra program began, Congress is faced with a real choice. It is a choice between a failed policy that promotes war and has already cost the lives of at least 25,000 Nicaraguan men, women, and children, and a Central American peace accord that charts a different and more promising path for the region.

The accord represents a political solution to what is fundamentally a political problem. Support for it will place our Central American policy back on a course that is truly consistent with US history and values. It will place the US foursquare in support of the rule of law, the right of self-determination, nonintervention in the affairs of other nations, democratic processes, and respect for basic human rights.

The regional peace plan emphasizes all those things US current policy does not. And it enjoys the backing and cooperation of the international community, as symbolized by the awarding of the Nobel Peace Prize to Costa Rican President Oscar Arias S'anchez, the plan's author.

Very few people continue to buy the Reagan administration's cynical argument that a vote for contra aid is a vote to further the Guatemala accord. Very few people believe deep down that that is the only way to ``keep the pressure on,'' to wring more concessions from the Sandinistas.

To the contrary, it is clear that more of the same will not do it. Only those unwilling to accept the reality of the last six months believe that more contra aid will do what six years of contra aid could not. The democratic Presidents of Central America do not believe that; neither do the American people.

Events since Aug. 7, when the peace accord was signed by the five Central American Presidents in Guatemala City, suggest otherwise. In six months, the accord has produced more concessions by Nicaragua than six years of funding the contras ever did.

It was not contra aid that reopened La Prensa; it was the Arias plan. It was not contra aid that created a forum for political reconciliation, headed by Miguel Cardinal Obando y Bravo; it was the Arias plan. It was not contra aid that secured the release of a thousand political prisoners, with the prospect of thousands more; it was the Arias plan.

It wasn't contra aid that initiated direct cease-fire negotiations; it didn't lift the state of emergency, or produce the decision to permit a monitoring commission to observe Nicaraguan compliance with the peace process; it was the Arias plan.

And it will do more if we give it a chance. I believe at this juncture Congress is prepared to do just that.

The vote this week is not going to be easy. It is never easy to say no to a personally popular president. But there is only one way Congress can come down on this issue.

Congress must say no to a request that would kill our best - our only - chance for peace in Central America. It is the only vote that makes sense.

Christopher J. Dodd (D) of Connecticut is a second-term member of the US Senate.