"Pearl the Plumber" led a short but ominous life. For two weeks, she starred in a one-minute advertisement that lobbyists broadcast on radio stations in the hometowns of key state senators from central Wisconsin.

"It used to be we had men's work and women's work. But now, women like me are doing all kinds of jobs, and doing them well, too," Pearl announced above the din of pipe-pounding. "But you know what gets my goat? A bunch of these highfalutin' Madison bureaucrats want to take us back to the idea of 'women's work' again.

"They call their plan 'comparable worth,' but Old Pearl here says it's a joke . . . a slap in the face to women like me who've worked hard to break down the old barriers."

Pearl's short run signaled the onslaught of pitched battle for supporters of Gov. Anthony S. Earl's comparable-worth plan. It would raise base salaries of about 15,000 women holding female-dominated jobs in the 43,000-worker state bureaucracy to put their pay on par with that of male-dominated positions that require "comparable" skills. Some would receive pay increases of as much as $6,000 a year.

The ads were part of an intensive, costly and apparently effective effort, led by the state's business community, to defeat a plan whose implementation seemed inevitable here and in many other states just a few months ago.

With the political clout of feminists and organized labor severely challenged by President Reagan's reelection, comparable worth -- a cause celebre of both groups -- is facing invigorated resistance.

"We got a free ride in 1984, with the business community not being geared up to fight us," said Diana Rock, national director of women's rights and community action for the American Federation of State, County and Municipal Employes. "I think this is going to be the year when we lose a few."

"As a general proposition, items that may be called part of the progressive social agenda are tougher to push now than they were before the 1984 presidential election," Earl said, "because people perceive, rightly or wrongly, that the electorate is moving right."

But opponents counter that, under close scrutiny, comparable worth is unworthy. "It's a concept that hasn't been thought out well. It's been pushed through. When it does stand on its own merit, they find that it's a very unstable concept," said Madison lawyer Frederick H. Miller, who is lobbying against the plan.

"They believe it, but they can't prove it," Miller said of the proponents' assertion that wage disparities between men and women are based primarily on sex discrimination and should be ended through base-pay increases. "I don't want the cure for my lame leg to be an amputation of my head."

Comparable worth goes to the floor of the Wisconsin State Assembly this week. Both sides expect it to be rejected in the House but approved by the Senate, most likely leaving its fate to a conference committee from both chambers.

The uncertainty is ironic. Wisconsin has a liberal tradition, and the state's ideological sister, Minnesota, is implementing, with little controversy, a comparable-worth plan approved for its state bureaucracy in 1982. Earl is a liberal Democrat, and his party controls both legislative chambers. Wisconsin also is a strong union state.

In a compromise aimed at easing passage, Earl halved his original $17 million request to finance first-phase implementation. Supporters have changed the plan's title to a proposal for "Correcting Pay Inequities Based on Gender and Race." The words "comparable worth" had become "buzz words," some said.

Such retreats were hardly imaginable a year ago. In December 1983, U.S. District Court Judge Jack E. Tanner ordered the state of Washington to raise salaries for workers in jobs dominated by women to correct "pervasive" discrimination among state employes. Under that impetus, which is under appeal, many states launched studies of the problem, set aside money for pay increases and broadened existing comparable worth statutes.

Half a dozen states have adopted plans and approved money to raise the wages of female employes in their bureaucracies. They include Idaho, which paid out $12.5 million in 1976 to adjust base salaries, with hardly a mention of "comparable worth."

"The word was not even used in the discussion at the time," said state personnel director Richard J. Hutchison. "I feel pretty good. I feel like we're about eight or nine years ahead of everybody else."

More than two dozen states, including Maryland and Virginia, have completed or started comparable-worth studies. Legislation calling for such a study is before the D.C. City Council. Los Angeles last month became one of the latest municipalities to approve a comparable-worth plan.

A 1984 study by the Rand Corp. found that, on average, women in the national work force are paid about 64 cents for every $1 paid to men. The report said the gap has been shrinking, especially between 1981 and 1984, and estimated that it could narrow to 74 cents per dollar by the year 2000.

Comparable-worth advocates urge closing the gap by evaluating jobs for such factors as education requirements, stress and working conditions.

When jobs are found to have comparable scores but different pay and the major difference is that one job is held mainly by men and the other by women, efforts are made to determine how much of the disparity is based on sex discrimination. Pay adjustments are made accordingly.

Comparable worth, sometimes called pay equity, often is confused with the less controversial concept of "equal pay for equal work," which contends that men and women holding the same jobs should be paid equally.

Opponents, who often label comparable worth "equal pay for different work," generally argue that all such job comparisons are subjective, and that the free market, not paid consultants, should be the primary determinant of wages. Comparable worth, they add, will not eliminate job discrimination.

"It simply throws money after the issue," said Jane Cahill-Tryon, whose firm, Cahill, Sweeney and Associates, is lobbying against passage of Earl's comparable-worth plan, claiming that it could cost twice as much as Earl has estimated.

Earl's proposal applies only to state workers, but private industry has become its major opponent. Business lobbyists in Wisconsin say they fear that comparable worth could spread to the private sector or simply drive up state taxes and further sour the business climate in a state that has lost 7 percent of its economic base since 1980.

Comparable-worth advocates pledge a narrow application.

"It really ought to be the law of the land, but I just don't think it's enforceable," said University of Wisconsin professor Dennis L. Dresang, chairman of the state task force on comparable worth. "We can only do it beyond the bureaucracy by example."

Earl's proposal, launched in the face of a possible employe lawsuit, is part of the bill for the state's biennial budget, making it more difficult for opponents to isolate the issue. Reclassification of jobs and pay scales would be done outside the regular collective bargaining process.

Contending that the comparable-worth argument is largely a smokescreen for a large union pay raise, its foes have proposed including all comparable-worth adjustments in the regular collective bargaining process -- with no separate funds set aside for comparable-worth pay raises.

"The union for the first time would have to decide which jobs it seriously believes are undercompensated," said Paul E. Hassett, president of the Wisconsin Association of Commerce and Manufacturers. "At the present time, whatever the study comes up with, it's a free ride."

Howard L. Fuller, head of the Wisconsin Department of Employment Relations, said such an alternative would shift responsibility to the unions for problems they did not create. "At this point . . . it is the state's responsibility to redress past wrongs," Fuller said.

Marty Beil, executive director of the Wisconsin State Employes Union, the major organization of state workers, said the alternative could pit male-dominated unions against female-dominated ones in a scramble for pay-raise funds.

"There's a real potential for some real divisiveness," Beil said.

In neighboring Minnesota, comparable worth at the state level has not fazed businessmen.

The Minnesota Association of Commerce and Industry, which said little about the 1982 statute and a 1984 act mandating comparable worth in municipal bureaucracies, has taken the precaution of opposing its spread to the private sector.

"I think it's peaked. I don't think comparable worth is going to spread like wildfire," said Francis Fitzgerald, the organization's director of labor-management relations.

The major new controversy over comparable worth in Minnesota has centered on police and firefighters, who want to be excluded from local comparable-worth plans. State law forbids both groups from striking and binds wage-setting procedures closely to arbitration.

In the past, local governments generally have accorded both groups better-than-average contracts because of their working conditions. The comparable-worth proposal would give less value to working conditions than to other factors.

Police and firefighters say that could result in lower pay increases -- and none at all if governments empty their pay-raise pots on comparable-worth adjustments.

"If a local government is allowed to plead poverty and not allow our raises, and our raises from the top jobs are given to the bottom, that's just skimming from the top to protect the bottom. That's intolerable for us," said Jerry Bridgeman, secretary of the 700-member Minneapolis Police Federation.

Rick Scott, state director of political action for AFSCME, said of the police and firefighters, "They're doing well under the old system, and they don't like change. They're frightened of it."