Every time attempts were made to produce a "new Nixon," events and personality conspired to reinforce the public memory of the "old Nixon." And not only because Nixon was Nixon. As a general rule, presidents are so well known, and their standing so mixed up with events, that efforts to make cosmetic retouches of personal image are almost bound to fail.

The new stance now being affected by Jimmy Carter may just come off, for its fits the flow of events and does no violence to the president's inner self. Even so, in moving to cut a different public figure, the president has embarked on a risky venture that could easily backfire.

The new-model Carter is easier to feel than describe. It is a matter, as Jody Powell put it at breakfast the other day, of "taking a somewhat firmer position," being "a little less accommodating." Cases in point include the threat to veto the farm bill, the strong stand on planes to the Middle East, and the tough speeches, during the recent western swing, on lawyers, doctors and the Russians in Africa.

The reasons behind this show of toughness are not in doubt. Carter has plunged badly in the polls and in the esteem of most other leaders here and abroad. The case against him is not bound up with any specific failing, since his presidency is unmarked by anything like disaster. Rather, there is a general feeling of weakness and incompetence, bound up with repeated changes of positions, usually made to accommodate some interest in the Congress or the public.

For reasons of political imagery, accordingly, it makes sense for Carter to be slightly more hard-nosed, to dig in in a visible way against the pressure groups. At present merely taking a more resolute stand should foster the impression that the president is truly in control.

One important substantive issue, moreover, reinforces the logic of imagery. In the past few weeks, inflation has emerged as the central concern of national and, to some degree, international politics. Given the inevitable rises in food prices, and the public dislike of government interference, there is not a great deal the Carter administration can do to arrest the rise in prices this year.

But a position of rhetorical firmness, a willingness to hit out at free spending makes sense. So the president is well advised on policy grounds to set his face firmly against raids on the public treasury, against overcharges by lawyers and doctors, and by labor and business. Indeed, Robert Strauss, the inflation czar, is just hoping some industry will announce a huge, far-out price increase that will provide the occasion for a wrathful administration to show its seriousness on inflation.

Finally, outspoken shots at fat cats apparently fit the president's character. He worked the populist themes well in the 1976 campaign. Newsmen with him on the recent western swing report that he was very much at ease delivering the wet mitten to the bar association in Los Angeles.

But there, precisely, lies the danger. Carter has in his nature a self-assertive, uncompromising streak. He can be mean and vindictive toward those who get in his way. Indeed, the reason he has had to do so much compromising in the past 10 months of his administration is that in the first six he took - before really knowing what he was doing - extreme moralistic positions on arms control, water projects, energy and half a dozen other subjects dear to important groups of powerful people.

The president still has to deal with those groups. He doesn't own the Russians, or the Congress or even the press and the liberal professions. If he strikes out carelessly, if he takes harsh positions, he will not build a new sense of competence. He will only reinforce the old image of a small figure in deep seas whose idea of governing is to lash the waves.