It's been so long since the Democrats won a big one, they weren't sure how to act.

Sen. David H. Pryor (Ark.), a southerner who declared early against Robert H. Bork, stood up at the Democratic Caucus lunch Tuesday and implored his colleagues not to gloat. He had been disturbed by a picture in the morning paper of Majority Whip Alan Cranston (Calif.) holding up a vote count that projected the defeat of the Supreme Court nominee.

The victory showed the Democrats that their old coalitions live and their issues still sell.

They had mobilized their constituencies -- or rather the constituencies had mobilized themselves -- and put on a sophisticated, disciplined campaign that showed that on constitutional matters the country is with them. Bork was shown through his writings to be the rock-bottom conservative, one of those right-wingers who hate government but love the state. By the state they mean the military and the police, which must be protected against uppity individuals who dare challenge authority. The country said, "No, thank you."

Certain givens that had fallen into doubt during the Reagan years strongly reemerged. The country wants no tampering with civil rights or the right of privacy.

Their leaders didn't exactly lead them. In fact, Democratic leader Robert C. Byrd (W.Va.) had to scurry to the mikes Monday to catch up with his followers. Twenty-eight senators had come out against Bork before he could breathlessly announce "Me, too."

Sen. Howell Heflin (Ala.), the only southern Democrat on the Judiciary Committee, was much looked to for guidance by his brother Democrats; but he spent his time in elephantine coyness before many cameras. Minutes before the showdown vote, he was remarking that he really couldn't say. His "no" vote was an anticlimax.

The southerners who held the key to the outcome kept their own counsel. They never officially caucused for fear of being found out -- and prematurely signaling what President Reagan could only see as a massive defection.

It is a new world. In 1984, Reagan made hay against Democratic presidential nominee Walter F. Mondale by portraying him as the captive of the special interests. But the words have lost their buzz. Interest groups, if large enough, are "constituencies" again.

Republicans threatened the Democrats with worse if they turned down Bork. They held up the specter of Orrin Hatch, the hard-line senator from Utah, as Bork's substitute. Reagan insisted on a floor vote because he said rejection of Bork would be an issue in 1988.

The Democrats held steady. Older members remembered 1969, when President Richard M. Nixon sent up Clement Haynesworth for the court. The Democrats, with their groups behind them, turned him down for his civil rights record. Five months later, Nixon tried again with G. Harrold Carswell, whose civil rights record was worse. The Democrats again said "no."

Haynesworth and Carswell were no more a campaign issue in 1970 than Bork is likely to be in 1988.

In the end, Nixon chose Harry A. Blackmun, a sensible moderate.

In their rejoicing, however, the Democrats can see that the unity and strength displayed in the Bork affair have not spilled over to their presidential prospects.

The night before the Judiciary Committee vote, the six remaining candidates gathered in Florida for yet another debate, this one on foreign policy. Sen. Albert Gore Jr. (Tenn.) came on like the national commander of the American Legion. The others, he suggested, are wimps who do not appreciate Reagan's forcefulness. He heatedly defended the Grenada invasion.

Gore aimed his fire at Massachusetts Gov. Michael S. Dukakis, and it was like shooting the wounded. The governor looked exhausted and stricken. He has come through the wringer of being fingered as the killer of Sen. Joseph R. Biden Jr.'s presidential dreams.

Gore is running for the southern hawk seat at the table, trying to fill the gap left by Sen. Sam Nunn (Ga.), who, of course, was told he could never get the nomination because he is too conservative. Since he quit, Nunn has been increasingly dovish, leading the Senate fight for more arms control.

A cruel irony is that Biden has been revived by Bork. He won bouquets from his brothers of both parties for his conduct of the hearings. On the day of the vote, he was crisp, fluent and in control. He spoke more clearly and effectively than he ever did as a candidate.

The sad lesson for the Democrats this happy-sad week is that their presidential candidates get better when they get out of the race.