John O'Connor, a 51-year-old small businessman who lives in College Park with a family of six and drinks in Beltsville with the Knights of Columbus, says he would like to vote for Edward Kennedy in Maryland's presidential primary, just as he voted for John Kennedy 20 years ago.

O'Connor says he agrees with Kennedy that the most pressing issue is inflation, and he deplores the decline of America's power under Carter. "The last worthwhile thing this country did," he says, was in 1962, "when Jack Kennedy told those Russian boats down in Cuba to turn around and go home."

But O'Conner will not let himself vote for Kennedy, because for him, there is a moral issue in the campaign. "His image is tainted," he says of Kennedy, "his family life is unstable and there's no way he can win with that."

Between sips of beer and talk of bowling and summer vacation, many of the middle-class Catholics who surrounded O'Connor at the Beltsville Knights of Columbus Hall one recent evening echoed his feelings. Kennedy's personal life, his stand on abortion, and his too liberal image had driven their votes back to Jimmy Carter, or even across party lines to Ronald Reagan.

"Jack Kennedy was a good Catholic president," declared one Reagan convert, who later that night would attend the Joseph P. Kennedy Knight of Columbus fund-raising dinner in Washington. "But even if Ted is a Knight, he doesn't live up to our standards."

In Prince George's, the feelings of those Beltsville Knights, whose members include many prominent local Democratic politicians, take on an added significance because they represent so much of the county's vote in this election year. More than 20 percent of the county's population -- or some 140,000 people -- is Catholic, and on Catholic issues, at least, Edward Kennedy has lost much of the support that helped his brother win the county with 58 percent of the vote two decades ago.

One reason for this, perhaps, is that fewer of the Catholic Democrats in Prince George's belong to the sorts of blue-collar trade unions that inspire bloc voting. "Catholics tend to lean toward liberal Democrats in other areas because many of them are blue-collar workers and union members," says the Rev. John Hogan, who is the rector of Sacred Heart parish in Bowie and the vicar of central Prince George's. "People here work for the government, and have very different attitudes."

The most Catholic community in the county is Bowie, where so many Irish Catholics live that one of their state delegates, Gerard Devlin, once remarked that "in Bowie, we don't have precincts -- we have parishes." But even Bowie, Devlin and others say, cannot be compared with the ethnic neighborhoods of Philadelphia, or Baltimore.

"We are far more cosmopolitan than other areas, and that's why there's not really a Catholic vote," said Rev. Ernest Gatta of St. Bernard's Church in Riverdale. "There are no historic Catholic communities here where people have lived for generations. Everyone comes from diverse backgrounds."

The peculiar demographics of Prince George's mean that Catholics are less likely to be attracted by Kennedy's economic policy than those in other states, and unlikely to feel an ethnic affinity with him.

That leaves the one issue that identifies thousands of Catholic voters in the county, and on which Kennedy has lost much of his potential support -- aborton. Maryland has one of the strongest antiabortion movements in the country, and the Prince George's Right to Life organization, which counts 12,000 members, is solidly opposed to Kennedy.

"Kennedy says he's totally against abortion, but his voting record is 100 percent wrong," says Ann Schutt, the leader of the county movement. "Choosing between Kennedy and Carter for us is like choosing between Hitler and Stalin. We are solidly behind Reagan."

Kennedy's only hope of winning over support from antiabortion supporters, observers say, is through local supporters who are running on his behalf as delegates, and promising to work for an antiabortion platform plank at the Democratic convention. "I'm telling people I will go to the convention both for Kennedy and for the issues," says state Del. Tom Mooney, who is one such candidate.

Closely linked to the abortion issue for county Catholics, however, is the larger issue of family morality, and Kennedy's image is often memtioned in the same breath as his record of voting for federal funding of Medicaid abortions.

"Ted Kennedy hasn't acted as a Catholic and as a man he's not a Catholic," said John Hogan, who voted for John Kennedy for opposite reasons.

"There is a group of Catholics who get uptight about Chappaquiddick and the other parts of Kennedy's past personal life," says Del. Frank Pesci, a Kennedy supporter. "The tradition has been that Catholic families are the most stable kinds of families. husband's don't cheat on their wives and wives don't become alcoholics."

Edward Kennedy's perceived personal failings, combined with philosophical differences, have turned away dozens of prominent county Catholics who contributed to a bloc vote for John Kennedy in 1960. "Whatever mystique Kennedy had for us is gone," said County Council member Francis B. Francois, who supported John Kennedy and now is a coordinator of Carter's reelection campaign in Prince George's.

Kennedy's supporters in Prince George's still believe he can win over voters on his own issues. "People here will still boil it out on the economic issues," says Council member Gerard T. McDonough, county co-chairman for Kennedy.

But, McDonough says, "the ethnic vote is not there as a bloc. John Kennedy was a big a deal for Catholics, but as you can see, the Catholic vote has gotten over that."