The Senate delivered a thumping defeat to the cause of trade protectionism yesterday, voting 57-42 to block a bill that would have imposed limits on steel imported into the United States.

The vote was a major setback for organized labor's hopes of curbing cheap imports to save American jobs, and it is likely to reverberate in next year's presidential election because it pitted labor, a key Democratic constituency, against the Clinton administration -- and by implication Vice President Gore.

The bill, which passed the House by a 2-to-1 margin in March, was fervently supported by the United Steelworkers of America union as necessary to protect the U.S. steel industry from an influx of imports that crested last year and contributed to several plant closings and thousands of layoffs. The imports came mainly from South Korea, Russia and other countries whose home markets shriveled amid the global financial crisis.

But despite predictions of a close outcome in the Senate, a motion fell 18 votes short of the 60 needed to prevent a threatened filibuster and move the legislation to a floor vote. Many senators heeded the arguments of the White House and the Republican leadership that slapping quotas on imported steel would blatantly violate international trade rules and risked triggering retaliation by other countries against U.S. exports.

Accordingly, the bill's opponents hailed the result as reassuring evidence that the political consensus for free trade, which has appeared to fray in recent years, remains strong.

Addressing the Senate immediately after the vote, Sen. Daniel Patrick Moynihan (D-N.Y.) called the bill's defeat "a solid affirmation of a half-century and more of American trade policy."

President Clinton -- whose aides repeatedly warned that he would veto the bill if it passed -- issued a statement welcoming the vote as "a reaffirmation of America's commitment to open markets."

But the White House's victory may prove costly for Gore's presidential ambitions because of the anger the controversy has aroused among members of labor unions, particularly the steelworkers union, a generous contributor to Democratic politicians. Steelworkers, gathered at a deflated post-vote party on Capitol Hill, voiced bitter disappointment and vowed revenge against the forces that had thwarted them.

In an interview at the party, union President George Becker condemned what he called "tremendous pressure put on by the administration" to win votes against the bill, and said his members are "tremendously angry . . . they don't understand how this administration could sit by and let their jobs go out the window."

But asked whether his union would withhold support from Gore, Becker said it is "too early to say." The labor movement's lack of an appealing alternative was underlined when Gore's only Democratic challenger, former senator Bill Bradley, said yesterday that he would have vetoed the steel quota bill if he were president.

Although some steelworkers at the gathering denounced Gore and said they wouldn't support him, many of those interviewed said the political implications of the vote were far from clear, and they noted resignedly that senators on both sides of the aisle had voted against the bill.

"I don't necessarily believe that this will necessarily hurt Gore," said Beth Luther, an organizer for the union in Indiana. "Most of us are willing to judge individuals on their merits." She added: "We had Republicans who surprised us [by voting for the bill], and Democrats who've been known for their pro-labor stance who didn't support us this time."

Jim Lee, a steelworker from Ohio, said: "If a guy's got 95 things right, then as mad as hell as I am about the other five, I won't forget about the 95. Sometimes you get half a loaf of bread instead of nothing, and the Republicans will screw me 95 percent of the time."

Administration officials had been worried that GOP senators would vote for the bill to force the president into the embarrassing position of vetoing it, thereby highlighting the split within the Democratic Party. But many Republicans cited their party's traditional free-trade views in opposing the legislation, including Senate Majority Leader Trent Lott (R-Miss.), who warned that it would "hurt businesses and farmers" that depend on exports. "It is starting down a path that is extremely dangerous," Lott said.

The steel industry and its supporters are still hoping to win enactment of legislation that would make it easier for an industry besieged by sudden import surges to obtain temporary relief under procedures consistent with international trade rules.