As a concerned citizen, Leon Gaidmore was downright angry last spring about interest rates -- at the time, the prime rate was nudging up toward 11 3/4 percent -- and he took his complaint right to the top.

When Jimmy Carter traveled here for a town meeting 10 months ago, Gaidmore, a retired toolmaker with silver hair and a white brush of a mustache, stood up and gave the president a piece of his mind. "Isn't this high interest most unfair to our young people?" he said. "Isn't this all wrong?"

Today, the prime rate has topped 16 percent, and Leon Gaidmore is still angry -- but not at the president. "I'm for Carter," he said this weekend in the unmistakable New England accent that made the sentence come out "I'm fah Cahda."

"I'll vote for him Tuesday because I think you know, he's a decent Christian gentleman. I don't know, interest, I don't think it's his fault. Gosh, everywhere you look, these banks, I mean, they run the country."

As a mother of six, Mary Kennan was disturbed last spring about inflation -- the annual rate then was 13.9 percent -- and she, too, complained at the town meeting. "I want you to know how concerned we are about inflation," she told the president in her brisk, all-business way. "It's attacking the American family . . . Can you tell me what your administration is doing?"

Today, inflation has zoomed to an annual rate of 18 percent, and Mary Kennan is more disturbed than ever. But in tomorrow's primary, "I'll vote for Carter," she says.

"I'd have to honestly say I can't remember how he answered me, but I think it was that he was doing as much as anybody could. And I think I mean, that's it. Sort of, inflation is a worldwide thing."

And so it goes among the people in this charming old seacoast city who peppered the president with snappy questions at the town meeting here last April. Most are still upset about pocketbook problems -- much more so, judging from two days of interviews, than about foreign affairs. But they have not channeled that distress into dislike for the man in charge.

There does not appear to be much burning enthusiasm here for Carter, but there is a general perception that he is probably as good a president as the country can expect.

"Well, I don't think he follows up on stuff much," said Forrest Snowden, a polite, well-informed high school student who complained to the president about college tuition. "But he's president, and presidents, most of them, are the same, you know, they do the same things, so he's probably, I think, okay."

Truth-in-journalism requires the caveat here that the people who turned out to talk with the president last year are not necessarily representative of New Hampshire, or of Portsmouth, for that matter. The local Democratic Party, which is controlled by Carterites, handed out some of the town meeting tickets, and many of the people who got their tickets in the League of Women Voters raffle probably came because they already liked Carter.

But they asked the president some hard questions and asked pointedly for specific answers. At the end of the session, Carter commented on that, saying -- in contrast to his present argument that his critics are "damaging our country" -- that the right "to disagree, to debate, to criticize a president . . . gives us strength."

Today most of those who questioned Carter in April have forgotten specifics of the event. What they remember is that Carter took his suitcoat off, answered their questions in a quiet, sincere manner and dealt politely with an antinuclear heckler.

"It's hard to remember what he even said," says Susan Hedman, a shy young housewife. "I'm trying to think of it. . . . I don't know, I was impressed with him. I don't know, I guess he's going a good job, it's just one of those things or whatever. I don't know what words to use about him."

Because Hedman, like many others, cannot really explain what lured her into the president's camp, she seems a likely prospect to be lured away if something better comes along.

"Kennedy, I mean, he's for socialized medicine, and I'm not for him. Brown, he's a sort of nut. But I think maybe Bush, or I don't know, Baker, or whatever, I might go with them if they're, you know, if they look like they'd be better than Carter."

(Sen. Edward M. Kennedy of Massachusetts and California Gov. Edmund G. (Jerry) Brown Jr. are challenging Carter; George Bush and Sen. Howard H. Baker Jr. of Tennessee are two of the GOP candidates.)

For the moment, though, people seem to be giving Carter the benefit of the doubt. They sympathize with the problems a president faces, and accordingly tend to excuse Carter for faults that spur them to criticize his opponents.

Emerald Jackson, an easy-going retired Air Force sergeant, and his wife, Vernis, a precise, articulate fourth-grade teacher, were among a small minority of blacks who met the president here. They say one reason they will not support Kennedy is his failure to support a black colleague.

"I don't like the trick he did to Ed Brooke," Emerald Jackson said. In the 1978 election, Kennedy campaigned for fellow Democrat Paul Tsongas in the Massachusetts Senate campaign. Tsongas unseated Republican Brooke, who was the Senate's only black member.

This comment reminded Mrs. Jackson that she was "disappointed" when Carter passed over a black woman, Mary Berry, when he chose the first secretary of education. But Mrs. Jackson defended the president: "He's human, he wants to be elected, he already has one black woman in the Cabinet. I just think for some reason that he's been pretty good as president."

People who met the president last April and came away unimpressed are equally nebulous as to their reasons.

"Let me put it this way, I'm not going to vote for the guy," said Dennis LaPointe, one of several people who asked Carter last spring about the Three Mile Island accident.

"I don't know, I just don't think he has -- he's completely blown it, I think, for us here in New England."

Like many others who took the trouble to go to a presidential town meeting, LaPointe says he is "really ticked off" about Carter's failure to campaign this year.

Even Leon Gaidmore, the president's backer, agrees with that. Gaidmore says nothing is more important than an open discussion among candidates. For that reason he has turned out this winter to see some Republican hopefuls and Saturday he and his wife, Margaret, went to a Kennedy rally.

Kennedy won over Margaret Gaidmore, who explained in breathless, mile-a-minute phrasing that she had decided "that Georgian can't do it, and I think, heck, I'll go with the Irish."

Mrs. Gaidmore was delighted at her independence from her husband. "He's always told me how to vote," she said. "You always told me, Leon, you know that. But now, there's woman's lib and I'm going my own way."

"Well, that's okay, there's no fight about it," Gaidmore said. "After 40 years we're not going to get a divorce over some politicians. We'll fight about something important."