General Motors and the United Auto Workers appear headed for a showdown over health-care costs. But the underlying story is that the American labor movement is headed for a showdown with itself.

Despite repeated efforts to breathe new life into the union movement, the ranks of Big Labor continue to decline – to a mere 12% of the work force, compared to about a third of the work force in the 1950s. In the private sector, only 8% of workers now belong to unions.

Union activists love to blame the problem on globalism and all that cheap labor in Third World countries. But the real reason is that unions are literally self-destructive, preferring short-term benefits to long-term growth. GM has steadily pared its work force and recently announced another 25,000 layoffs in the coming year. Yet when asked about a relatively modest cut in health benefits, UAW President Ron Gettelfinger airily told the New York Times that GM is a “huge corporation” and that nothing could be done until the current contract expires in 2007.

From the viewpoint of an elected union president, this “what, me worry?” strategy makes a certain twisted sense. Most of those laid-off workers will go on to find other work and lose their vote. Mr. Gettelfinger’s job is thus safe even at sharply lower levels of auto employment. UAW membership of about 650,000 is less than half what it was in the 1970s. Michigan is still heavily unionized and boasts high wages – but it’s also leading the nation in unemployment, at 7.1%.

Not that one should waste much sympathy on the American automakers themselves. After all, they agreed – reflecting their own short-term interests – to the union contracts that are killing them. And much of their product line lacks sizzle. But when you have fallen behind on the cost curve, it’s very difficult to focus on – much less find the money for – style and innovation.

The deepening split within the AFL-CIO reflects a belief among hard-line activists that President John Sweeney just isn’t trying hard enough to recruit new members. But the UAW has been trying hard for years – with no success – to unionize the foreign automakers that have set up shop in right-to-work states across the South. As its experience clearly demonstrates, the problem is not so much lack of effort as lack of appeal.

The workers in the Nissan, Toyota, and other plants already make good money and good benefits, thanks to a level of productivity that produces good profits.

Moreover, union political clout is in sharp decline, victim both of prosperity and the collapse of the argument that what’s good for the UAW or the AFL-CIO is necessarily good for America. Unions that once heralded themselves as the vanguard of social progress are now widely seen as just another special interest, indeed, a wholly owned subsidiary of the Democratic Party.

Union officials have no answer to the competitiveness issue other than morally odious protectionism against the poor in other countries or trying to persuade American taxpayers to pick up the tab for their Cadillac-level benefits. But voters have rightly shown little appetite for engaging in serious trade wars, and they are smart enough to see that a national health system not only doesn’t save money – Europe is sinking beneath the fiscal weight of its national health systems – but doesn’t work.

Even Canada’s supreme court pointed out last week, in ordering Quebec to allow the re-establishment of private health-care providers, that the country’s single-payer health monopoly is costing lives.

Public-sector unions were a plus for the labor movement until recently, but as the fiscal consequences become clear – many states and municipalities would be instantly bankrupt if forced to recognize their real health and retiree liabilities – the loss of public affection is likely to be just as stark. As the middle class flees to the non-union suburbs and right-to-work, the power of the public-employee unions may actually increase for a while – but power over what? Detroit has been reduced to begging for suburban police and fire assistance merely to hold its annual July 4th fireworks display.

And that may only be a precursor to what is coming, so perverse have the dynamics of unionism become.

Mr. Bray is a Detroit News columnist.