RONALD Reagan has had many politically happy weeks since he got to the White House, but he must have enjoyed the one that preceded the New York primary election with particular relish.
It was a week during which the two most likely Democratic candidates for the task of contending with Mr. Reagan in November were busy not only cutting each other up but doing it in a manner that raised a doubt about the fitness of either one of them to become president of the United States.
There is an essential point about the presidential office which many a politician tends to forget in the heat of running for it. The point is that the country needs in the office the wisdom to discern the long-term interest of the country and the courage to stand for it even when the popular clamor is the other way.
The clearest case that comes to mind was Harry Truman sacking Gen. Douglas MacArthur. For Mr. Truman the deed was frighteningly unpopular. The general had become a popular hero. He was the darling, particularly, of right-wing Republicans, who were thinking of running him as their new presidential candidate. To dismiss him would be not only to rouse a firestorm of popular abuse, but also provide the opposition party with a popular ''martyr.''
You won't find an objective and reputable student of American history and political science today who questions the wisdom and the necessity of the MacArthur dismissal. It was Harry Truman's finest hour.
The general had committed flagrant insubordination. He had defied direct orders from his commander in chief. He was attempting to overrule Washington on national policy. The authority of the presidency was at stake. The doctrine of civilian control over the military (essential to democracy) was also at stake. Mr. Truman would have become a figurehead President had he tolerated further insubordination.
He did what was essential to the authority of the office. He dismissed one of the most popular generals in American history. And he took the heat he knew would engulf him for doing it. That was political courage.
As this present campaign progresses I keep looking for evidence in the behavior of the various candidates both of the wisdom that can perceive the long-term national interest and the courage to pursue it no matter how unpopular it may seem to be at the moment.
Right now it's in the long-term interest of the US for the President to keep alive a moderating role in the Middle East. Walter Mondale and Gary Hart were trying to outbid each other over the issue of the location of the US Embassy in Israel. Were it to be moved to Jerusalem, as both urged, Washington's role as a potential mediator would be damaged, perhaps irrevocably.
Right now it's in the long-term interest of the US for the President to retain control over nuclear weapons negotiations with the Soviet Union. Walter Mondale and Gary Hart were arguing over who was more devoted to the nuclear freeze. A freeze would limit the negotiating options of a president - any president.
If either Mr. Mondale or Senator Hart is actually President next year, he will be embarrassed and his range of choice narrowed on both Middle East and nuclear weapons by what he was saying in New York last week.
President Reagan, at the White House, urged Congress to avoid the embassy issue. He kept quiet about nucleAns.
Mr. Reagan could look very much more like a president during the week by watching Mr. Mondale and Mr. Hart behaving in unpresidential manner.
To be fair it must be remembered here that during the 1980 campaign Mr. Reagan berated President Carter over the Panama Canal treaties and virtually promised to reverse Mr. Carter's China policy.
As President Mr. Reagan has honored and carried along the Panama Canal treaties and revived the China policy. Presidents often have to repudiate in office policies asserted during the campaign. I still want to know whether Mondale and Hart would be able to do the same if either reached the White House.