The sale of the Washington Diplomats to Madison Square Garden Corp., formally announced yesterday afternoon, may be the first step in bringing a baseball team to Washington.

The Washington Post has learned that Gulf and Western Inc., owners of Madison Square Garden, is among the leading contenders to purchase the Baltimore Orioles, who are for sale.

David (Sonny) Werblin, president of the Garden, said yesterday that a baseball team was certainly a possible part of the Garden's future in Washington.

"We're in the business of purchasing sports franchises and operating them," Werblin said."If the opportunity to buy a baseball team comes up, we'll take it."

Werblin said he had not contacted any current team owners about a possible purchase. "I wait for them to contact me," he said.

During the two months of negotiations between Diplomats President Steven I. Danzansky, who represented the former club owner, San Juan Racing Inc., and Garden representatives, the possibility of a baseball franchise for RFK Stadium was discussed on several occasions, a source said.

Another source, close to Gulf and Western, said yesterday that once a tentative decision to keep the Diplomats in Washington was made, discussion of a baseball franchise came up.

"The Garden has always believed in trying to have more than one franchise in a facility purely for economic reasons," the source said. "It's simply logical for them to want a baseball team if they are going to be operating in Washington."

Werblin was noncommital when asked yesterday if he thought Washington could support a baseball team. "If Washington will support a baseball team, it should have one," he said. "This is a good sports market, we're convinced of that. Right now, most of the loyalty is to football. But if you produce a winner, you can change that."

Werblin said at yesterday's press conference that the new owners would seek "to make the Diplomats the best soccer team in the world as soon as possible.

"That doesn't always mean spending big bucks," he said. "If all you had to do to win was spend big bucks, then everybody would win."

The presence of the Garden and of Gulf and Western in Washington brought local politicians to the press conference in force.

Mayor Walter E. Washington welcomed the Garden people to Washington and was joined by Democratic mayoral nominee Marion Barry (referred to by Danzansky as "Mayor-elect Barry.") City Council Chairman Sterling Tucker and Democratic council chairman nominee Arrington Dixon.

Werblin said that Danzansky will remain as president of the club and that no changes will be made - at least for now - in the front office. He also indicated that Coach Gordon Bradley would have complete control over the recruitment of the 1979 team.

Although Werblin would not talk about how much the Garden is willing to spend on players. Bradley said he told his scouts overseas that they could now look at "a higher class of soccer player."

Dips General Manager John Carbray still is in Chicago at league meetings and Werblin made a point of saying that Carbray's absence "means nothing."

Carbray, general manager of the club the last two years, had a verbal agreement with SJB to remain another three years. Whether he returns in 1979 apparently still is undecided.

"I plan to be here a lot during the next few weeks," Werblin said. "Basically, I'll be taking inventory to see what we have available to us right now before we start making moves.

"I can assure you, though, that whatever we decide, Gordon Bradley will be in charge of putting this team together." Bradley and Werblin were friends in New York when Bradley was with the Cosmos, and Werblin referred to him as "my soccer mentor."

The new ownership has agreed to a 15-year stadium lease with the D.C. Armory board, an agreement that guarantees that the Dips will stay in Washington for at least five years.

RFK Stadium has 55,000 permanent seats and Washington indicated that with the Garden working there, expansion might be necessary.

"We're hoping that you will make this Madison Square Garden South." the mayor told Werblin.