In the garden of Blair House yesterday evening, the newly presented White House Fellows, barely a week into their respective jobs, kibitzed with the seasoned powers of Washington.

Chief Justice Warren Burger, Energy Secretary James Edwards, and Interior Secretary James Watt could be found chatting with various Fellows over cocktails and hors d'oeuvres. Secretary of State George Shultz breezed in for quick greetings and then hurried into a waiting limousine. National Gallery of Art director J. Carter Brown and Kennedy Center head Roger Stevens and wife Christine (both in formal attire for a later engagement) also showed up to meet the Fellows.

Also present was Sol Linowitz, President Carter's Mideast negotiator, who is now practicing law. "I didn't envy Philip Habib," he said. "I knew the agonies involved. I was talking to him a couple of days ago. Anybody who has been through the anguish doesn't wish to go through it again."

Of this year's class, retired vice admiral James Stockdale, chairman of the President's Commission on White House Fellowships, said, "They're not any less idealistic than the classes before. But we're now seeing a group of young people who want to make the system work. They're not rebels."

Stockdale was the host of yesterday's reception along with White House Chief of Staff James Baker, White House Deputy Chief of Staff Michael Deaver and National Security Adviser William Clark.

A dizzying array, indeed. "Let me tell you," said Scott Gration, 30, a White House Fellow and a U.S. Air Force captain who has been teaching the Kenya Air Force how to fly the F5 jet fighter, "the transition from Nairobi to Washington is a big one." He lived outside Nairobi in a town called Nanyuki. "The big social event there was watching the cars go around the roundabout."

There are 14 White House Fellows this year, with the highest percentage of women since the program started in 1964. They survived a long, competitive application process and have come from various professions to work for a year at top levels in government.

Some of their hosts never made it to the party. "I was listed as a host with three other people who didn't show up," said Stockdale, chuckling. "But with good reason." All three were said to be flying back from Utah with President Reagan and would try to come if they returned in time.

But had they shown up, they might have been peppered with questions about Reagan's defeat yesterday as the Senate joined the House in overriding the presidential veto of the supplemental appropriations bill.

"I voted for the president," said Sen. Jeremiah Denton (R-Ala.), "but I didn't think he had the most well-chosen thing to make an issue of. I didn't tell him I would vote him when I talked to him on the phone." Who called to enlist Denton's support for the president's veto? "The president, Dole, Meese," Denton said. "But no arm-twisting. It was all very friendly." Denton dismissed this as a serious blow for the president. "Not with that close a vote in the Senate. It was really a draw."

Other officials downplayed the significance of the vote. "It wasn't a blow," Watt said. "It was a disappointment."

"I'm sorry it happened, but it has a silver lining," said Richard Viguerie, publisher of Conservative Digest. "He can go to the public and say conservatives don't have a majority in Congress. He can say, 'I really do need more conservatives in Congress.' " This week, Viguerie's magazine announced that according to an unscientific poll, three-quarters of its readers felt the president shouldn't run if someone more solidly conservative were available. But last night Viguerie was enthusiastically portraying Reagan as a man who can "snatch victory out of the jaws of defeat . . . He's still the best president we've had this century . . . It's not surprising that when it gets close to the elections that he started talking about the issues that brought him to the White House."

Elizabeth Dole, assistant to the president for public liaison, hadn't yet talked to her husband, Sen. Robert Dole (R-Kan.) about the upset. "I'm disappointed," she said, "but we have a good record. You can't win every battle." Dole, who has a Fellow in her office this year, applied for the fellowship during its first year. "There were 3,000 people and I made it all the way to Airlie House the site of the intensive grilling of prospective Fellows and the finals and then proceeded to lose it."

Even in this rarified atmosphere people talked about more than just politics. For instance, some Fellows wanted to know what Burger thought of Justice Sandra Day O'Connor. "She's doing fine," he said. "Some people ask me, 'Does it make a difference to have a woman on the court?' No, it makes no difference, except the place is more civilized," he said with a smile, then added, "but it was always civilized."

Asked later if he were looking forward to going back to that place the first Monday in October, he replied, "I have no choice," smiled, and walked out of the garden.