Reubin Askew, former governor of Florida, has to be ranked an extreme long shot among the announced candidates for the Democratic nomination for president. Gallup and other pollsters show him with less than a 2 percent rating among Democratic voters.

But at least Askew knows what it means to stick to a principle, which is more than I can say for Alan Cranston, John Glenn, Gary Hart, Ernest Hollings, Walter Mondale and Morris Udall.

The principle to which I refer is a commitment to resist protectionist legislation, to which these six pay lip service, but nothing else.

The Washington Post asked Askew and the others for their views on local-content auto legislation, introduced at the behest of the United Auto Workers. This legislation, which has passed the House, would allow foreign automobiles to be sold here only if a high share--up to 90 percent--of American labor and parts had been used in their manufacture.

The legislation, of course, is directed entirely against Japanese cars, which have run American cars into the ground--mostly because they are better cars, and have a price advantage (despite the long sea voyage from Asia) because Japanese labor unions haven't extorted excessive wage rates from the Japanese car companies.

Democrats are running scared on this issue, aware that high unemployment will stir up as many as 200 protectionist bills in the new Congress. Thirty-four of the 57 new Democrats in the House got there with the help of contributions from the UAW, which again will focus on the local-content bill, this time concentrating on the Senate.

Politicians wring their hands over the possible disappearance of the American auto industry, when what they really mean is the disappearance of American auto jobs--not the companies. Regardless of Japanese competition, robots and automated processes on American assembly lines will replace thousands of UAW members, who never will get their jobs back, even when the number of American cars grows back to something closer to normal.

So when The Post asked traditionally-free-trade-oriented Democratic candidates what they thought about the obviously discriminatory local-content legislation, which is sure to bring retaliation, only Askew could summon up enough courage to say he is against it.

"I am concerned about the plight of American auto workers and the American auto industry," Askew said. "I firmly believe the American auto industry can modernize and succeed. But I am also concerned about the American consumer. And, as a former U.S. trade representative, I do not believe we will ensure the success of the auto industry or protect consumers by establishing domestic-content requirements for motor vehicles sold in the United States."

Askew is right: The Congressional Budget Office calculated that local-content legislation might save 70,000 auto jobs, while losing 220,000 as other nations retaliate against American exports. Should the legislation become law, the average price of cars (U.S. and foreign) would rise at least $1,000 and possibly as much as $3,000 by 1985.

But listen to the way that the leading Democratic candidates waffled on this issue:

* Cranston: "I support the domestic-content legislation. . . . If selectively closed markets do ultimately harm employment, then we can take some comfort in the fact that the Japanese and Europeans--who retain enormous barriers to U.S. exporters--will be the first to feel this pinch and to alter their policies."

* Glenn: "We cannot defend our national interests with fast foods and video games. . . . Companies that enjoy sales benefits in our open markets should invest, produce and pay taxes here as well. That is the point of local-content legislation."

* Hart: "I have not cosponsored the domestic-content legislation. . . . But if it proves to be the only way to avoid the collapse of our auto industry, I will support it."

* Hollings: "I favor the content proposal, not so much to put Japan on notice as to put the Reagan administration on notice. . . . Our automotive industry--given time to retool and update--can be fully competitive again. That policy worked for our textile industry, which again leads the world in productivity."

* Mondale: "This country cannot continue to act as though free trade is a reality. The American autombile industry is getting clobbered. . . . As a result, I favor domestic-content legislation."

* Udall: "Why is a free-trader like Mo Udall cosponsoring and voting for an admittedly protectionist measure like domestic-content legislation? . . . It is better to fire a warning shot over the bow today than to risk a full-scale trade war later."

It would be hard to put together a more transparent collection of special pleading. Only Hart, among this group, admits that the key flaw in the legislation is that it doesn't do anything to make Detroit more competitive.

As Washington attorney Carl Green observed when participating in a Harvard program on U.S.-Japan relations, Japan's trade barriers do not by themselves explain its huge trade surpluses. Increasingly, the United States is turning into a service economy--and running up large surpluses of its own in the current account as distinguished from the trade account. Beyond that, there has been the high-interest-rate pattern here, overvaluing the dollar against the yen. And for many years, union wage increases have outstripped productivity, putting American products at a price disadvantage.

All these considerations are ignored by a blinders-on acceptance of local-content legislation. His fellow Democrats would do well to draw on the practical experience of Askew in the trade field. Like the current trade ambassador, Bill Brock, Askew knows that local content raises a question of a violation of international trade treaty arrangements. Retaliatory measures could be thrown against some $15 billion of U.S. exports of aircraft, electrical components, food and other products.

To oppose local-content legislation doesn't imply that the new Nakasone government in Tokyo shouldn't do a better job than did Premier Suzuki in ending Japanese trade discrimination. But it is folly to perpetuate the myth--as do Cranston, Glenn, Udall, Mondale and Hollings--that local-content blackmail will result in the opening up of Japanese markets, or that such an opening, desirable as it is, will solve Detroit's problem, or materially reduce the U.S. trade deficit with Japan. We've got some work to do here at home first.

Yet Japanologist Ezra Vogel observed that the American power structure increasingly has begun to equate Japanese economic successes with unfairness, and to swing--as do the Democrats mentioned earlier--into an emotional, protectionist stance. Save for Askew, this is exemplified by what they're doing by supporting local-content laws, all the while protesting that they somehow are fighting a deeper protectionism. Instead, they should be trying to find a more rational way out of the impasse that would preserve, instead of shattering, the crucial bilateral U.S.-Japanese relationship.