One the same day last week that Associate Justice Potter Stewart made public his decision to step down from the Supreme Court, the House of Representatives passed a measure extending the life of the Legal Services Corporation, which runs the federally financed program providing lawyers for the poor. The vote in the House was 245-137, but that is short of the two-thirds majority that would be needed to override the veto presidential counselor Edwin Meese has said he would recommend to President Reagan.

The fact that the president, who does not see any compelling need for the continuation of the Republican-created program of legal services for the poor, is the same president who will soon be filling Potter Stewart's "swing seat" on the Supreme Court is something to give you pause.

Reagan has been hostile to the legal services program since its beginning in the Nixon administration. When legal services lawyers went to court on behalf of impoverished Californians and won judgments that the Reagan administration was illegally denying them their benefits under federal and state programs, the then-governor was furious. A compromise of sorts was negotiated, but it did not dispel Reagan's hostility.

Now, as president, he is proposing that the Legal Services Corporation be abolished and its funds cut off. Instead of the staffs of specially trained lawyers now available to help poor people with their problems, the administration is saying that their legal needs can be met by the states -- using scarce funds from the reduced federal social services block grant -- or by private law firms doing charitable work. Meese suggested at the University of Delaware law school that taking care of the legal problems of the poor might provide some good practice and relief from the tedium of the classroom for third-year law students.

The best comments on this brand of thinking came, not from the bleeding-heart liberals, but from some of the Republican members of the House who have intimate knowledge of the program.

Rep. Tom Railsback of Illinois, who is about as sentimental as barbed wire, helped manage the bill in the House."The Americans we are talking about, it is fair to say, are poor," he remarked. "They represent a disproportionate number of American minorities and they represent a disproportionate number of America's elderly citizens . . . . The subcommittee, Republicans and Democrats alike, made this decision that the 29 million poor Americans should be able to sit down and discuss their legal problems with an attorney.

"Every lawyer in this body," the Illinois Republican said, "and in the nation for that matter, is fully aware of the fact that to successfully use our system of justice, you need the assistance of an attorney -- and to deny these people their assistance is the very same as denying them access to our system of justice. If we do this, then I believe the consequences may be serious, not just for the poor, but for our entire system of government."

Rep. M. Caldwell Butler of Virginia, a Republican as conservative a his name, said: "I remind my colleagues that the Legal Services Corporation is a Republican initiative, which had its earliest beginnings when Lewis Powell Jr. was president of the American Bar Association in 1965 . . . . Lewis Powell Jr. is now a justice of the Supreme Court . . . appointed by a Republican president.

"I share the view Mr. Justice Powell expressed . . . in August 1976." Butler said, and quoted him as follows: "Equal justice under law is not merely a caption on the facade of the Supreme Court building. It is perhaps the most inspiring ideal of our society. It is one of the ends for which our entire legal system exists. And central to that system exists. And central to that system is the precept that justice not be denied because of a person's race, religion or beliefs.Also, it is fundamental that justice should be the same, in substance and availability, without regard to economic status."

Ronald Reagan does not understand or accept that proposition. He almost certainly will use his veto on the legal services bill. And then he will decide who sits on the Supreme Court with men of the character of Justice Powell. It is something to ponder.