It is "almost impossible" these days for a president to score high in public opinion polls, according to a person who has been trying -- Jimmy Carter.

" . . . most of the decisions that have to be made by a president are inherently not popular ones," Carter said, according to a White House transcript released yesterday. "They are contentious."

During an interview with out-of-town editors and broadcasters, Carter discussed the problems of his office in one lengthy answer that ranged from political science to presidential frustration.

Carter had been asked whether it is reasonable to expect a president to rate high in the polls given the complexity of international and domestic affairs.

"My guess is, in this present politica environment, it is almost impossible," said the president, whose favorable ratings have hovered between the low thirties and the high teens, depending on the poll.

He went on to talk of unpopular decisions that must be made and his dissatisfaction with the way some polls are conducted, and the way news is reported by some organizations, including The Washington Post.

Carter began with the issues.

"There is not a single vote to be derived from the evolution of a national energy policy," Carter said.

Carter said: " . . . highly motivated consumer groups . . . or environmentalists can never be satisfied with any acceptable proposal that has a chance to be approved by the Congress, and the oil companies, and all those who are from producing states, can never be satisfied with a compromise that's acceptable to Congress and is able to be passed.

"And for the president to espouse a balanced program naturally arouses the condemnation, certainly the opposition, criticism at least, of those highly motivated opinion-shapers."

Carter went on to talk about times when he had to make "unpopular" decisions. He cited the Panama Canal treaties. A poll had shown that only 8 percent of the public favored a new canal treaty, he said, but his three predecessors and all State Department experts believed a new treaty was necessary. Carter said he worked for the treaty and its ratification even though he knew it was "patently a losing political proposition."

Carter also received some support from an unusual source yesterday, Sen. John Danforth (R-Mo.). In a speech prepared for delivery in Columbia, Mo., Danforth suggested that "we let up on President Carter." He said he was "terribly concerned about the incessant drumfire of criticism directed at the president."

He said he means "that we have overdone the criticism, that it has been too unrelenting and that we have impaired the man's capacity to fulfill his responsibilities."

Carter said his popularity rating was also hampered by inflation, which he called " an uncontrollable situation." He said the inflation rate is about the same as 1974 and that it has fluctuated in recent years from this level down to about 6 1/2 or 7 percent.

The annual inflation rate in 1974 was 11 percent. It was running at 13.2 percent in July.

But he conceded that while inflation may be hurting him now, it also helped get him into the White House in 1976. "I think the fluctuations in the of the economy are one thing which hurt President Ford just before the election in November of 1976," Carter said.

Carter had campaigned against Ford by attacking inflation. He said in Portland, Ore. in the fall of that year, that the 6 1/2 percent inflation rate "must be changed . . . it's a constant daily robbing those who are retired . . . Democrats have always believed and have proven that we can have low inflation rates and low unemployment at the same time."

Carter also said that "the press - and without criticizing the press - is not going to emphasize the successes" of an administration. He cited his as an example. Emphasis in the media was on his administration's setbacks in Congress, he said, and not that out of the 15 programs he said he was personally involved in, "9 1/2 or 10 of them" had been enacted.

Carter cited the case of the trade bill. When President Kennedy's trade bill was enacted in the 1960's, toppling trade barriers and setting standards, it was considered his major domestic policy achievement, Carter said.

"We passed one this year that is broader and, I think, superior in every way to the one that was passed in 1962 or 1963," Carter said. "In The Washington Post, which is a major focal point here for the promotion of news stories, there was not a single word when the Congress passed that bill."

The White House later explained "the president meant there was no separate news story. Passage of the trade bill was given two paragraphs on page three in the congressional digest (On Capitol Hill) for that day."

Carter also criticized an analysis method used by Louis Harris and the Associated Press/NBC poll, although he did not mention them by name. It is the technique that labels evalutions of "excellent" and "good" as "positive" and "only fair" and "poor" as "negative." In the latest AP/NB poll, Carter was given only a 19 point "positive" rating.

Said Carter:

"Where I come from, which is southwest Georgia, if you ask these days, 'How do you think the county school superintendent is doing?', if somebody says, 'I think he's doing a fair job', that is high approbation."

Carter said he believes other factors will prove more important in deciding the 1980 presidential election than "the relatively transient public opinion polls."

What is more important, he said, sounding like an announced candidate, is that the public will look at the record of accomplishments and "what we hope to accomplish in the future." And - in what sounded like an intended comparison with his possible challenger, Sen. Edward M. Kennedy (D-Mass.) - Carter said the public will also look at "your own character assessment, the reputation that you have for being steady in an emergency."

One Carter assistant conceded that it might be a theme that will be repeated by Carter and his stalwarts as the campaign heats up, explaining: "It's a positive, rather than a negative, statement."