When the voters of Florida go to the polls for today's presidential primary , more than one-fourth of them are likely to be senior citizens. Judging by extended conversations with two dozen of them here, many in that large group are dissatisfied consumers of the American political process.

Older people account for 40 percent of St. Petersburg's population, which make this a disproportionately elderly place to sample opinion. But the elderly are the fastest growing group of American voters, and also the most avid participants in politics of any age group. So the voices of St. Petersburg are worth listening to.

An informal and unscientific sampling of senior citizens here provides some comfort for President Carter's reelection campaign but not much, and it offers no comfort at all for practitioners of politics in general.

"I've watched presidential elections since 1942," observed J. K. Kyle, 77, a retired lawyer from Madison, Wis., in a characteristic comment. "I can't remember any other campaign in which, at the beginning of the campaign, there wasn't one guy who I thought, I'm for him, and I'm all for him, he almost suits me.' That isn't true this time. There isn't one in the whole outfit."

Kyle voted for Carter in the 1976 Florida primary " to get rid of Mr. Wallace," and again that November to get rid of "a Nixon appointee," Gerald Ford. "I'm going to vote for [Edward M.] Kennedy in this primary on the issues. He's got a record on legislation. I don't think much of his personal connections, but I'll vote for him as a protest against the lack of program of Carter. I'll probably vote for Carter in the general election . . . ."

Kyle was one of a group of 10 people who had lunch with a reporter to ruminate on the current political situation for a couple of hours.

Only one subject evoked sustained, intense reaction from this group: Congress. Most of the comments on thepresidential candidates echoed Kyle's ambivalence, but there was no ambivalence about the House and Senate. Fran Sucliffe, 68, a participant in the same discussion, put it this way:

"A good way to correct the [country's] problems is to just declare the Congress a disaster area and start all over again."

Earlier, two other groups of St. Petersburg residents at the Sunshine Center, a popular city-run facility for retirees, talked in similar terms about the candidates and about Congress. Though all three groups voiced a predictable range of disagreements, there was a surprising consenus that this presidential campaign offers no heroic figures, and that Washington seems stymied, not least because of a recalcitrant and selfish Congress.

Passion came into these conversations mostly in negative ways. These senior citizens are much surer about what displeases them than about what -- or -- whom -- they are for.

Here are some examples:

Kay Henry of Steubenville, Ohio, a Republican: "The system isn't working like it was. Anybody that's honest will tell you that."

Sutcliffe: "To me there has to be a system" for selecting a president.

G. L. Boynton: "All that money spent [on campaigning], it doesn't do no good. They shouldn't let that kind of money be spent on it."

Augusta Gerberich: "Another thing that's been on my mind lately -- with all their ideas about cutting this and cutting that, I would like to know if anybody in Congress ever suggested cutting their own fancy salaries. . . ."

Henry: "They're raising it all the time."

Gus Zittell: "I think somebody suggested cutting the salary not too long ago -- he's not there anymore, if you know what I mean."

Clifford Howard: "They get more in expense money than they get in salaries."

Henry: "They get more expense money than they get in salaries, and if they don't get enough they steal it. What are we getting in Congress? A bunch of nitwits."

Boynton: "I believe the cure to this thing is to clean house, put a new bunch in there. Let's try a new bunch, everybody, even get the janitor out of there."

Not surprisingly, inflation is one subject that is raised repeatedly by these older Americans, most of whom are living on incomes they can no longer control. But there was substantial disagreement here as to how seriously inflation is really hurting people, and whose fault it is.

William B. Farmer, 73, is working here in a program that helps old people find jobs. Last week he got a job for a 77-year-old man as an elevator operator in a resort hotel. "What permeates everyone that I see that is looking for a job is, 'I was able to get by, but now with the cost of living the way it is, I'm running behind all the time and my savings are going down all the time and it isn't going to be long before they are absolutely gone. What am I going to do'?"

Farmer continued: "Now they can't help but feel it's the administration -- I'm not trying to pick out Carter or any other individual -- but the government is not doing the right thing. Not that they want more welfare, they just want to have inflation under control."

Agnes C. Miles, a native of Pittsburgh now in her 70s, disagreed with some passion: "I'm sick and tired of always hearing about 'fixed incomes.' My bank account, ain't going less. I'm paying more, same as you are, but my interest [on savings] is higher, too."

Boynton saw a more serious situation:

"It's the worst I've seem it in my 77 years. Of course during the Depression it was a different story. But now, with all these built-in things, it shouldn't be this bad. They've got all kind of programs.

"I ain't heard nobody say where this inflationm come from and how it got here. Just like it got here, it looks like you ought to could cure it. Must of been something that caused it to be here, and that cause, if you worked on it, look like that would cure it."

Charles F. Carroll thought it was more complicated than that, as did many others: "It's no longer one country -- you got to look at the whole international picture. Believe me it's a staggering problem if you want to sit down and analyze it."

Not once in any of these conversations did someone say he or she had a good answer to inflation. Not once did anyone suggest that a particular candidate for president was likely to solve the inflation problem.

Inflation is not a unique frustration. These senior citizens repeatedly said they weren't sure about many different issues, because they didn't know what to believe. "Is '60 Minutes' truthful on the television?" an exasperated Charles Furlone asked in one heated discussion.

"I think the news media form opinions," said Clifford Howard, retired proprietor of a New Jersey printing business. "They print what they think, and on TV they say what they think, and they form the opinion of the people . . . Like who's ahead -- they'll say all right, Reagan's ahead, so everybody gets the idea that Reagan's going to win, or Carter's going to win, and everybody wants to back a winner, so the people are switching back and forth."

"You'd be lost," interjected Augusta Gerberich, a former teacher and wife of a retired college professor. "You wouldn't know anything if you didn't have the TV and the newspaper."

"That poses another question," added Gus Zittell, a retired employe of Mobil Oil. "Are you getting the correct information via those media?"

Evelyn Watts, a volunteer worker in St. Petersburg who lives on a pension of $5,000 a year, was a Republican for 43 years, but switched to the Democratic Party because of the Vietnam war. "I'm working my butt off for Carter, and I hope to God he gets it," she said. "I think he's the one man that's been in there trying."

Watts is worth quoting because her enthusiasm for a candidate was nearly unique in these conversations.

A few of these people are Kennedy supporters, but interestingly, even the staunchest refused to defend Kennedy's personal character. Furlone, challenged by others on this issue but fiercely loyal to Kennedy, said morality wasn't the issue -- "that's beyond the point."

Among the Republicans interviewed, Reagan held a distinct but unenthusiastic lead. Among all the senior citizens in these conversations, the Republicans who got the best notices was John Anderson. Several Democrats said they'd like to vote for him.

If there were a consensus on the prsidential campaign, Farmer stated it:

"There doesn't seem to be any one candidate that everyone can come up for -- so many don't like Carter, or don't like Kennedy, or don't like Bush or whatnot. There doesn't seem to be anyone that the people can rally around and say, "This is the guy we want.'"