The wonderful thing about running for president, once explained a man about to do just that, is that the candidate is granted, for at least an instant, the nation's attention and the chance to state strongly: this is what I believe is really important; this is what we should be about as a people. The candidate was right. The television cameras and the microphones do follow presidential candidates and other important politicians, providing them with a platform from which they can enlighten us or frighten us, from which they can help set our national agenda.

One unpleasant item on the national agenda has been the very public termination of the public career of Sen. Harrison (Pete) Williams (D-N.J.). It was a sordid story, made even more so by the senator's alibi: it could happen to anybody. Sure it could--to anybody who, upon being exposed to the FBI's sleazy con man, Mel Weinberg, could resist the irresistible urge to walk fully clothed through the nearest car wash in hopes of scrubbing away the residual slime. Williams was able to resist that urge.

It was not always this way with Pete Williams. Before there was a Mel Weinberg in his life, there was a Magdaleno Diemas. In June 1967, Magdaleno Diemas was 29 and a farm worker on strike in the Rio Grande valley of Texas. That year, striking farm workers were not popular with the state's powerful governor, John Connally, or with the state's prestigious law enforcement agency, the Texas Rangers. There was sworn testimony from two doctors about the injuries to the head and chest of Magdaleno Diemas when he was allegedly kicked and beaten by Texas Rangers. A clergyman from the state council of churches testified that he had seen two Texas Rangers hold Diemas' face only inches away from a passing freight train.

That testimony was not heard in a courtroom. No, that testimony and more about the brutal existence of the farmer workers was taken in hearings across the country by the Senate subcommittee on migratory labor. The nation slowly learned that the average migrant worker in America worked 85 days a year and received an annual income of $922, that our fellow human beings left large chunks of their lives in scorching fields so that the rest of us could have a salad bar. Vegetables, we were obliged to remember, did not grow in the A&P; they were harvested by families whose dwellings were usually unsafe and unsanitary.

Because the subcommittee took on the powerful growers and influential local leaders, the cameras and the microphones covered the fight. The plight of the previously powerless farm workers was placed on the national agenda, thanks in large part to the efforts of a Senate subcommittee and its chairman, Pete Williams.

Of course, that was 1967, 15 years ago. Television has changed, and so has our politics. Now television news tells us how to cope, how the use of low- calorie hashish is on the rise among the beautiful people and how we can feel better about our being selfish. Now, our politics proclaims, and we listen, that government is most definitely not an instrument of social justice--that government is a blood-sucking and clumsy invader that punishes the industrious and rewards the indolent.

Our current national agenda includes very little on the suffering of the less powerful. Very few fun couples are found in migrant labor camps. But, because public attention was directed and public law was written, those camps are better than they were. Pete Williams, before the scheme, had dreams. He made the plight of the farm workers his cause and an item on the nation's agenda. Pete Williams made a difference for a lot of people ; who will never know his name. A senator can do that.