Washington came up with enough voting support yesterday to force a delay until Oct. 15 of the North American Soccer League owners' decision on the site of the 1980 Soccer Bowl.

The bidding for the league championship game was expected to come down to Vancouver and Detroit but D.C. Mayor Marion Barry, encouraged by club officials of the Diplomats, addressed the owners yesterday in New York in a last-ditch bid to get the game for RFK Stadium.

From nowhere, Washington now emerges as the favorite to get the game played in Giants Stadium the last two years. Washington entered the picture after Tampa Bay decided to drop out of contention for the game.

Vancouver, which won this year's Soccer Bowl over Tampa Bay, 2-1, on Saturday, has the best attendance average of the three bidding cities but a stadium capacity of only 35,000.

Both Washington and Detroit lack impressive attendance averages -- drawing about 12,000 each -- but the Express had a much better facility to offer in the Silverdome.

"That's true they do have the Silverdome," said John Carbray, the Washington general manager.

"But we all feel that Washington is an event town, and if we can get the business community involved and put together a package to make the Soccer Bowl a week-long festival, we can get the game and we can do a good job with it. What's more, having the game would be a huge plus for our frnchise."

The league also will consider a number of proposed changes today, most notably involving, scheduling. Under a proposal by the Diplomats, the league would expand from a 30- to a 34-game schedule and each team will play rivals in its own division four times each -- twice in each city.

For the Dips that would mean four games each with the Cosmos, Rochester and Toronto, against whom they had a 1-5 record this season.

"The point is to build up rivalries, something that we really haven't done in this league," Carbray said. "Look, Tampa and Fort Lauderdale would love to play each other four times; the same with us and the Cosmos."

In addition, if the proposal succeeds, and it appears to have an excellent chance, it will mean a lot less travel for league teams and a large saving on travel expenses. That was a monumental burden for most clubs the past season.

The longer schedule would stretch the regular season through August, with the playoffs taking place for most of September.