Politics, it is often said, is show biz, and as the race for the Senate goes into its final week before the primary, voters here are being treated to some performances from nationally known stars.

On the Republican side, in the role of Elder Statesman in Failing Health, is Jacob K. Javits, facing his first primary fight in his 24-year Senate career. On the Democratic side are two of the more glamorous faces in American politics: faded but flashy former mayor John V. Lindsay and consumer advocate and former Miss America Bess Myerson, facing off against Watergate heroine Elizabeth Holtzman, playing herself in the role of Plain But Smart.

There was a political gaffe by the governor to add last-minute tension and drama -- he referred to the Javits seat as "a Jewish seat" -- slick commercials by the top directors in their field and newcomer conservative contenders in both camps to give the social critics something to chew on.

And then there's the dialogue, bitchy and acerbic as only a New York election can be. Lindsay: "If one wants to buy an election, as Miss Myerson is doing. . . ." Myerson: "I guess, John, I learned it from you."

Cruel, really, considering that Lindsay gave Myerson her first and only political appointment, but great political theater.

Dramatic as the issue of the reelection of Javits may seem, it is not the issue that has taken stage center in this primary. For one thing, Javits is still viewed as the front-runner among the Republicans. For another, even if he loses on the Republican ticket, he will still be on the ballot as a Liberal Party candidate.

The audience interest in this race then is with the Democrats.The contest, according to the polls, is between Holtzman, the 38-year-old congresswoman from Brooklyn's 16th District, best known nationally for her role on the House Judiciary Committee during the Nixon impeachment hearings, and the stylish and wealthy Myerson, who served -- under Lindsay -- as New York's commissioner of consumer affairs.

Both women seem to be competing for the same urban, white, middle-class constituency, while Lindsay, who is trailing, appears to have his strength among urban blacks and upstate New Yorkers. The farther people are from New York City, the more they like Lindsay, or so the joke goes. Also that in upstate New York Lindsay has two things going for him: one, he's not a woman; two he's not a Jewish woman.)

Once the most charismatic man in local politics, times are not good for Lindsay in this election year. In one television commercial, Lauren Bacall -- who is also seen on TV endorsing Fortunoff jewelry -- says huskily that she is not voting for a woman this year, she's voting for Lindsay, "the underdog."

Lindsay's other celebrity backer is Muhammad Ali, in training for a fight, who Lindsay claims told him, "First you win -- then I win." All things considered, this is one of the more poignant statements of the year.

The latest poll, taken by the New York Times, showed Myerson with 38 percent, Holtzman with 27 percent and Lindsay behind with 15 percent. A fourth candidate, conservative Queens District Attorney John Santucci, who had a scant 8 percent, is not viewed as a serious contender.

A simple plurality in the Sept. 9 primary will decide the nominee.

So the stage is cleared for Holtzman and Myerson, in a campaign that seems based not so much on issues, but on past records and alliances -- and of course on that old and intangible crowd-pleaser presence, or, if you will, image.

Myerson, who has never held elective office, attacks Holtzman for continually blocking military expenditures. Holtzman hotly rejoins that she wants a strong defense, but not at the expense of social services.

Thus they focus their attacks on the past. Holtzman charges that Myerson used her consumer expertise to "sell out to big business." Myerson insists that Holtzman, who often votes in the minority, is unable to form coalitions effectively or "make friends."

Making friends, at least as a street campaigner, is no problem for Myerson.

She's well-known to New Yorkers, not just for her work as consumer affairs commissioner in 1969-73, but as the local girl who rose from poverty in the Bronx to become the first Jewish Miss America and a columnist and a TV star.

Six feet tall, elegant in simple clothing, with her fashionable glasses worn low on her nose, Myerson is the glamor girl -- for many the favored daughter. She's mobbed like a film star when she walks down the street, and she works the crowd well.

In midtown Manhattan's diamond district, she puts an arm around a visitor from Israel and poses for a picture, makes liberal use of Hebrew and Yiddish, or -- in a prototypical and cozy New York City gesture -- silently fingers a woman's gold necklace in simultaneous assessment and admiration.

The recognition she receives on the street, however, while one of the strengths of her campaign, is also one of the liabilities. Myerson has to convince the voters that she is not simply another celebrity, but that she can be an informed and effective legislator. (That problem was not helped, in the early days of her campaign, when she was quoted as saying she was not aware enough of the issues to comment.)

She also has another problem. While promoting herself as a consumer advocate, Myerson has come under attack for her work for big business. That work has helped make her wealthy -- she acknowledges she is worth about $4 million, and last year declared an income of $493,000, the highest of the Democratic candidates.

Of that figure, $265,448 came from the Bristol-Myers Co., for whom she worked as an "outside consultant." She has also been a consultant for Citibank and Warner Communications.

This, her campaign manager David Garth, who once handled Lindsay's campaigns, has tried to turn into an asset. Myerson's slogan: "She knows government. She knows business. She knows how to get things done . . . for New York."

Myerson's campaign has been helped by the $800,000 she has spent on TV commercials and by the endorsements of the three top Democrats in the state, for each of whom she has campaigned in the past. They are Mayor Ed Koch, Gov. Hugh L. Carey and conservative Sen. Daniel Patrick Moynihan, many of whose beliefs she echoes.

Carey's endorsement, since his comment about the "Jewish seat," is not as much of a plus as it might have been, and after that remark Myerson's office canceled the news conference that had been scheduled to announce the governor's endorsement formally.

"I think Miss Myerson has a habit of cutting people who help her the most," Lindsay said of this, in a tone of sour counterpoint that has become his unattractive trademark in the campaign. He has, as well, criticized her TV budget, saying that the more he examines it the "more evil" he thinks TV advertising has become. He readily admits that he, under Garth, also used TV, but this does not dissuade him. "It takes one to know one," he says.

Holtzman's campaign problems have been very different from Myerson's. Rather than having to overcome the problem of the wrong image, her campaign team has had to work simply to give her statewide visibility.

Where Myerson is an effusive campaigner, Holtzman is more restrained, a smile and perhaps a handshake. Where Myerson is glamorous, her glasses a dramatic prop, Holtzman is prim -- what columnist Murray Kempton once called "a Jewish nun." She wears sensible shoes, high-necked dresses, carries a dowdy crocheted handbag. Her glasses she uses to see through. Nobody, compaigning calls her a beauty -- quite the opposite.

"You got my vote. My wife, she's voting for the beauty parlor," a man confides in a Long Island shopping mall. Yells another voter, "If brains count more than beauty, you'll get it."

Holtzman takes these comments sometimes with amusement, some with irritation. "People don't respond to that," she says. "I've been in Congress for 7 1/2 years, and people really don't care what lipstick you wear or where you get your clothes . . . people respect me because of my record . . . they remember me from Watergate . . . they know I'm not going to smile at them and sell out."

She refers to her record often: to her start in elected office eight years ago, when she "fought the whole political machine" and defeated Emmanuel Celler in the Democratic primary after he had served in Congress 50 years. That she wrote the legislation to get an extension for the ERA and shepherded in through a tough Senate, as well as House. That her investigation of corrupt lunch programs in New York sent 19 people to jail. Of the fact that in the upcoming Abscam trial of Rep. Frank Thompson, part of the government's evidence will reportedly be a tape of Thompson telling the FBI that Holtzman is "too honest to trust" in her role as chairmanof the House immigration subcommittee.

In this recital, there is something of the lone wolf in Holtzman, something of a brave and solitary person against the unenlightened majority. "While others kept silent, I asked Gerald Ford hard questions about whether the Nixon pardon was a deal," she says. And, "alone, I went to court to challenge Richard Nixon's bombing of Cambodia."

Her record, she insists, will win her the election. And when she hears the voters -- a man in a shopping center could say only that he would vote for Myerson because she had some undefinable characteristic termed "whammy" -- she shrugs.

"A minority," she says.

If voters want dazzle, of course, they can always go with Lindsay, at 58 the best-looking face in politics and still the only male human being to look good in a white short-sleeved dress shirt. The man should be in movies and has been . He's also a novelist, a former television correspondent and is a lawyer.

Before this he had a career in government, as assistant to then-attorney general Herbert Brownell in 1956 and 1957, as congressman from Manhattan's "silk-stocking district" from 1958 to 1965, as mayor or New York City from 1966 to 1973. His mayoralty has been disparaged by some, most recently by Mayor Koch, who, campaigning for Myerson, has taken to speaking of Lindsay as the mayor "who took the city to the brink of bankruptcy."

Lindsay's campaign has centered on the economy -- "it seems out of control" -- and on the breakdown of the quality of life in the city -- "this city is polarized, dangerously polarized."

He also has pressed for tax credits for parochial schools and yeshivas. But he has spent a great deal of his campaign sniping at Myerson, both for her work as a consumer consultant and for the money she spent on television commercials ($800,000 to Lindsay's $200,000). "The Senate is becoming a house of lords and it's getting worse."

The Republican primary offers another sort of drama. It pits Javits, 76, longtime liberal who has held political office for 30 years, against conservative Alfonse D'Amato, 43, the supervisor of the Long Island town of Hempstead.

Like Javits, D'Amato has the backing of a second party, the Conservative, so that win or lose he also will be on the ballot this November.

The race has become an emotional one because of Javits' health; Javits has charged angrily that D'Amato is "phonying up pictures to make me look like I'm dying."

Javits' health is an issue. He helped make it so in February, when he announced his candidacy. He disclosed then that he has motorneuron disease, a chronic condition, usually progressive, that damages nerves, finally causing muscles to wither. Javits says that the disease has affected his legs and made walking difficult, but does not affect his mental ability or his ability to do his job.

The commercials of his opponent this past month suggest otherwise.

"Now 76 and in failing health, he wants six more years?" says the voice-over in one commercial. Javits' camp has countered in its commercials. "I know my age . . . all the spirit of '76 . . . I know my health . . . I would not serve if I could not run," says Javits in one commercial, calm and confident.

In person, however, Javits appears more fragile and tired than he looks on the screen, and he is defensive and waspish on matters of health.

"You have any questions, you speak to my doctors, miss," he snaps. (he has five.) Nor is he interested in introspective questions as to why, after over 30 years in office, he must continue to run. "Time of grave crisis," he says. And, "I wouldn't turn my back on the people when they need me."

In debate with D'Amato he adopts an attitude of intellectual condescension and irriation -- perhaps somewhat understandable when facing a man who uses words like "restraintful," a man who interrupts conversations to talk back to Javits' commercials on television, and says Javits helped make New York "the Cadillac of welfare states."

They squabble about the things the conservatives and liberals squabble about: ERA and abortion (Javits pro, D'Amato against); defense spending (D'Amato missile and B1 bomber; Javits wearily replies that he's getting tired of that charge, that he in fact voted for the MX missile and only against the B1 because he "felt it was a turkey" which was at any rate about to become obsolete.

But the subject they returned to and the press pushes them to return to, is the subject of Javits' health and the campaign. Javits asserts then that he has never seen a campaign "based on such crudity as looking forward to a man's decease."

D'Amato counters that the photos of Javits never were doctored, that certainly no impropriety was ever meant, that really the question of health is a valid issue. Privately he cannot resist a comment for the press.

"Actually in life, he looks worse than the picture," he says.