Going into opposition, the tug to do so is upon me. I have watched the president become less and less the Ronald Reagan of Campaign '80 and more and more the captive of the Republicans of furrowed brow. These are the Republicans who believe that the key to political greatness is a nice white shirt and a good word from one's political opponents. They believe that politics is the act of the anesthesiologist: dope up the opposition, put a smile on his face. Assure him that you are with him in spirit, and do nothing to arouse his unease. Be pragmatic!

Thus, these pragmatic Republicans walk around the White House with furrowed brows. It is not easy to keep Tip O'Neill happy, especially if most of the members of your party think O'Neill is bent on buying votes with the assistance of the U.S. Treasury and the sempiternally alluring poetry of "The Greening of America." It is more difficult still to get sweet words from the millionaire mannequins of the evening TV news. They see themselves as the heirs to Robespierre. They are certain that, owing to the economic policies of Ronald Reagan, people off in the direction toward which their corporate chauffeurs head at night are selling apples and preparing barricades. Sweetening up O'Neill and the mannequins of evening news while avoiding national bankruptcy is a grueling task.

These pragmatic Republicans have been keeping a careful eye on the Oval Office, and when they see their boss reading the editorial page of the Wall Street Journal they gasp. They have pretty successfully isolated him from his former allies, and they want him to utter no agitating thoughts about "getting the government off our backs" or "strengthening our defenses." They want him to fudge on still more of his campaign promises. They agree with the Democrats that taxes should be raised in a recession and that this huge milch-cow state created by the liberal Democrats should continue to graze contentedly on our tax dollars even though it gives less and less actual sustenance for every heaping bushel basket of dollars munched upon.

Well, after a series of interviews with some of our amiable president's supporters from the last campaign, it appears to me that many of them are snatching a line from the late Al Smith and taking a walk. It is fitting that Al Smith's name should be invoked. He was a conservative Democratic governor of New York in the '20s. The people I have most recently interviewed were once Democrats, too; though they were liberals in the 1970s they came to deplore the growth of tyranny in the world and the growth of statism at home. They have been called neoconservatives, and in 1980 they led a large contingent of conservative Democrats to vote for the present regime.

This evolution of liberal Democrats into neoconservatives is one of the most important developments in recent political history. In the 1980 campaign, Ronald Reagan led an amalgam of blue-collar workers and traditional Republicans, all of whom favored increased American security, a revived economy and an end to such liberal abominations as affirmative action, reverse discrimination and quotas. The neoconservatives have been a formidable force in articulating the views of this constituency. But carrying out their wishes would make the Democrats and their friends in the media irritable, and so the pragmatic Republicans have labored to turn Ronald Reagan into Gerald Ford. Is such a thing possible?

Apparently Norman Podhoretz thinks that it is. Podheretz is the neoconservative editor of Commentary magazine. He recently has written a very important book, "Why We Were in Vietnam," that thumpingly demolishes all the guff about American deviltry during the Vietnam War. And now he has a major piece coming in The New York Times Magazine wherein he registers his alarm that the administration's foreign policy has been amazingly weak, especially in responding to Poland, the Middle East and Central America.

Podhoretz is not the only neoconservative to enter strenuous caveats about the present listlessness of White House policy. Irving Kristol, the editor of The Public Interest, strongly criticized administration foreign policy in the Wall Street Journal two weeks ago, and he now believes that the White House has been ''fumbling" many of its domestic initiatives--particularly its promises to cut back the coercive social policies of the Carterian Age.

The unease of Podhoretz and Kristol is widespread, not only among neo-conservatives but also among traditional conservatives. These people had believed that the Reagan presidency presented the Republic with an historic opportunity to reverse a national decliine. The pragmatic Republicans see the Reagan presidency as a swell way to make a living. They believe their job security will be enhanced by soothing the opposition. Now their problems are about to multiply.