While the joyful campaign workers were toasting Ronald Reagan tonight with victory beers, down the hall at the Holiday Inn some joyless ex-campaign workers were packing their bags and going home.

Reagan, on the brink of a great victory in the New Hampshire primary, decided to change the top horses in his campaign organization.

He fired the controversial campaign director, John Sears, in mid-afternoon. Then two Sears stalwarts, press secretary Jim Lake and national political director Charlie Balck, quit in sympathetic protest. By nightfall, a total of seven campaign aides had joined the exodus.

"We're leaving! We're leaving the whole state! John is gone! Jim is gone!" exclaimed a press aide as she packed furiously. Jim Lake was her boss.

Meanwhile, in a happier setting, the candidate's suite, Nancy Reagan let out a whoop and hugged her husband as they watched the TV returns showing him whomping George Bush in what was supposed to be a close contest.

John Sears was not around to celebrate. The controversial campaign director, who has clashed often with other staff members on how to package Reagan for the 1980 contest, was cooling his heels back at his home in Arlington, Va., his phone off the hook.

The swarm of campaign reporters, used to the inside-track treatment from Sears & Co., wandering around interviewing each other and trying to sort out the new players.

A major reason for booting Sears, it is said, was his "Imperial Candidacy" strategy in Iowa, which kept Reagan, the oldest campaigner on the trail, largely hidden. After the defeat in lowa, former press secretary Lyn Nofziger, who had been axed because of Sears' maneuverings, observed: "This just proves you can't run a rose garden campaign -- without a rose garden."

But in New Hampshire the story was roses for Reagan. According to a top assistant, the plan to eliminate Sears from command developed some time ago, but the candidate waited for an appropriate "window" when it would neither lose votes before the primay nor seem like post-mortem desperation.

The new executive vice chairman and director is William J. Casey, a New York lawyer who was chairman of the Securities and Exchange Commission during the Nixon adminstration.

The Sear's departure represented according to some insiders, a victory for the vigorous, out-front campaign approach Reagan followed in New Hampshire. This strategy, after the disappointment in Iowa, was urged upon Reagan, by Gerald Carmen, the New England coordinator, even as Sears thought it would make Reagan look undignified.

When Carmen's strategy seemed to be working, Sears was on his way out as master strategist, according to a top aide.

Carmen, with the bland assurance of a political who won the argument, would not speak ill of the departed advisers. "Going to miss'em all," he said. Then he turned his tongue on the evening's bigger loser, rival candidate George Bush.

"The silk stocking got a setback tonight," Carmen chortled.

Rep. Mickey Edwards (R-Okla.), one of many congressmen for Reagan who made strong protests about Sear's handling of the campaign, said, "I'm delighted to see Sears go."

"As I've spent the days traveling around the country in behalf of Reagan," the congressman said, "I get complaint after complaint about the way Sears has been handling things. They're saying: 'Whose side are those people on?' I've seen charity balls organized better than this."

Meanwhile downstairs in a packed ballroom waiting for their hero was a decidedly blue-collar crowd of Reaganites who felt no evident sympathy for the ex-manager.

Ray Caron, a truck driver from Manchester, had spent the whole day driving people to and from the polls. "He's the only guy for us working people," Caron said. "He's going to do something about our taxes."

In this crowd there were no tears for Sears. "I'm glad to see Sears is gone. He was the fella that cost Ronnie Iowa," said Alfred e. Gagnon, an auditor. Several other echoed that.

Reagan was one of the few around his headquarters who declined to call it a "firing."

"I wouldn't call it a firing," he said in an interview. "It was a case of a resignation there. There are always differences of opinion in a campaign."

When Reagan and his entourage moved through the sea of people around 10:30 p.m., he voiced a rallying cry that was a pointed reference to the underlying battle over strategy.

"This was the way to campaign," he said, "meeting the people of this country, and this is going to be that kind of campaign."

The buoyant candidate announced to his joyful supporters: "Nancy and I are flying on to Vermont -- and we won't need an airplane."

On his way out of the crowded ballroom, a young woman gushed over Reagan's movie star face.

"Oh what a wonderful face!" she exclaimed. "I wish now I hadn't voted for Carter."

At one point in the evening, Sear's replacement was trotted out to chat with the press. He seemed quite vague. "I can't remember," Casey said on the question of when he was asked to take charge of the campaign.

They kept putting on the official explanation that the campaign had to reduce its expenses and restructure the organization and Casey was the one to do it, not Sears. But many in the campaign had been left in the dark and were stunned.

Bay Buchanan, the national treasurer, who said they had spent close to $10 million by the end of January, said she was "absolutely shocked" at the late afternoon events. "I had absolutely no idea."

John Sears had a jolly, easy-going lunch with press pals only to come back to a 2 p.m. meeting with Reagan, Black, Lake and Casey and be handed his hat.

Ironically, this came at a time when Sears looked like he was on the upswing after the dark days of Iowa. He is credited with having masterminded last Saturday's Nashua debate, a theatrical crouhaha which apparently added to tonight's victory.

After the Nashua debate triumph, John Sears was too cool to gloat.

"Ah, just another day on the campaign trail," he said at the time.

But then Sears didn't know his days were numbered.