The news that there is a commandante in the White House, a staff member who expedites the contra war against the Nicaraguan government, has caused not a ripple in the pond of public opinion.

He is Marine Col. Oliver L. North, an Annapolis graduate and Vietnam veteran. His job on the National Security Council staff is to keep the contras' morale high and private funds flowing into their war chest.

President Reagan, when questioned about this astonishing development, replied airily that no law was being broken. The chairman of the Senate Select Committee on Intelligence, David F. Durenberger (R-Minn.), was equally detached.

It could be, you might think, a matter of more than passing interest that someone at the right hand of the president is promoting hostilities against a government with which we have diplomatic relations.

Not two months ago, the president protested that he did not seek the military overthrow of the Sandinista regime. In order to bring down the House, which for three years had resisted his secret war, he promised to resume talks with the Sandinistas.

Obviously, he had no intention of doing so. Thanks in part to North's helping hand, as we now know, the contras are raking in money and raiding deeper into Nicaragua. Stories of contra atrocities are recounted. Nobody seems to mind. Twenty-nine U.S. religious protesters who gathered to pray at the Nicaraguan-Honduran border were kidnaped by contras and held for 24 hours. So what?

Now, you will say it is August and Congress is out of town.

But for the Democrats, it is always August; and Congress, at least in terms of opposition, is permanently out of town. Except on the odd budget matter, Reagan does not have to consider them in his calculations. On questions of national security, Democrats are told, absolute acquiescence to the president is the road to salvation.

As a source of political opposition, the Democratic House has flopped. House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) has strong feelings about Central America, but he is busy with his memoirs, and his colleagues are scheming about his successor, so concerted action is unknown.

The House sold out on Nicaragua on June 26, when it voted $27 million in humanitarian aid for the contras. Members gathered the tatters of their integrity about them and insisted that the Central Intelligence Agency not administer the funds. But it neglected to say that the National Security Council should not take a hand in running the war, and now everybody is at the beach or on a junket, so no fuss is heard.

The possibility of sliding or sneaking into a general war in Central America is not on the national agenda. Nor is the arms race, which once was. A recent Soviet offer of a test ban was summarily dismissed by the president as a cheap propaganda ploy, and no promiment Democrat rose to suggest the matter be explored, and it has vanished.

The attorney general and the secretary of education fulminate against the Supreme Court over the place of religion in American society. The uncomeliness of two Cabinet members, who might be better concerned with the fate of the public school system, is scarcely remarked. The same attorney general further calls the civil rights organizations "a pernicious lobby," and, for all the response, he might as well have been talking about the weather.

Only two events have counted lately. One was the baseball strike, which caused no end of angst and many pompous pronouncements about the statesmanship of Baseball Commissioner Peter Ueberroth. The other was the capital concert of Bruce Springsteen.

Some argue that the national torpor on the deficit, nerve gas, Star Wars and other matters that will determine the future of the planet merely ratifies last November's election. The public wants to be entertained and diverted and leave larger questions to Reagan.

The problem may be, however, that the evaporation of serious political opposition makes dissenters feel eccentric or isolated. And, of course, only the official view is amplified. There is no Democratic spokesman. The opinion of Jimmy Carter is less solicited than that of Richard M. Nixon. Walter F. Mondale, who as the last nominee is at least the titular leader of the Democratic Party, has disappeared from public view, the loss of 49 states having relegated him to irrelevancy.

Theodore Roosevelt called the White House "a bully pulpit." It's now the only pulpit, and that's why it's August all year 'round, politically speaking, in the world's greatest democracy.