Jimmy Carter has 34 months and 18 days of his first term still to go. Yet he is the target of criticism and attack at home and abroad such as few presidents have suffered. Within his own party the gloomsters are saying privately that he will be a one-term president and that what will happen in 1980 is anyone's guess.

In this century perhaps only the luckless Herbert Hoover faced such a reaction. As the worldwide recession deepened, Hoover yielded to the demands of the protectionists and approved the Smoot-Hawley tariff act raising barriers against foreign imports. In 1930, the second year of Hoover's first and only term, that spurred the economic decline, which soon became the worst depression the West has ever known.

Carter has thus far stood firm against present protectionist demands, although it has been far from easy. As substitute, his trade negotiator, Robert Strauss, has arranged "voluntary" deals on steel, television sets and other products, responding to the claim that they represent unfair competion from Europe and Japan.

Hardly a day goes by that AFL-CIO President George Meany doesn't rush into the White House to demand protection for the unions from what he sees as a flood of unfair competition from overseas. And who elected you if it wasn't my people? he demands.

The president has also stood firm for a resolution of the Israeli-Egyptian peace negotiation, with an end to further Israeli settlements in the Sinai. That is in opposition to Prime Minister Menachem Begin's conviction of Israeli sovereignty dating from biblical times. That means opposing a lobby far more pervasive than the AFL-CIO.

The latest blow to Carter's reputation has come through his off-again, on-again handling of the neutron warhead. That whole contorversy has, in my opinion, been blown up out of all proportion to the facts. The warhead has for several years been a potential weapon in the American arsenal, and both its lethal capacity against enemy troops and its lack of destructiveness to the environment have been exaggerated.

But the neutron flap, with its repercussions in Europe, illustrates how ill served Carter is by those around him in the White House. The emphasis on his positive posture toward production and even deployment of the warhead could hardly have happened without the efforts of his loyal courtiers. Here, they were saying, was a president with the strength of decision ready to stand up to the bluster of the Soviet Union and the doubts of the disarmers at home.

Then, when out of his own troubled concern ovr the perils of the arms race and the morality of a weapon of still untested lethal potential he went the other way and decided to posepone production, the reactionwas bound to be violent. The spate of news stories from Europe in recent days about lack of confidence in Carter's ability are reaction to the neutron up and down.

More serious is the bargain that the president struck with Sen. Dennis De-Concini (D-Ariz.) to gain a vote for ratification of the first Panama Canal treaty. That bargain meant his acceptance of the DeConcini reservation asserting the right of U.S. military intervention in Panama, if necessary to keep the Canal open. The reservation was adopted by a vote of 75 to 23.

That is such a flagrant denial of Panamanian sovereignty that it is likely to mean the end of the treaties. Even if Gen. Omar Torrijos wanted, with his supposed dictatorial powers, to quiet the forces of protest, it is doubtful that he could.

So that adds another score against Carter. The political fallout is all too clear. With an almost knee-jerk reaction, Republicans who speak with the loudest voices attack anything - domestic or foreign - the president is for. Long gone are the days of Sen. Arthur Vandenberg and his pronouncement that politics stops at the water's edge.

The unhappy herbert Hoover was constantly embattled with the Democratic Congress. From the perspective of nearly 50 years it must seem that he was deeply rooted troubles growing out of the first world war that no president in office could have stopped the slide toward catastrophe.

From a similar perspective, if we are granted that much time for judgement Carter also may have been confronted with nearly insoluble problems. Coming to the presidency with little experience in high policy and with a curious concept of the office as a moral persuader, he has come up against a stone wall of intractability.