WASHINGTON'S CAMPAIGN for a major league baseball team has run into a minor disappointment -- though not of any fans' doing. Hopes for progress next month have been dashed by concerns about a possible strike. A scheduled Aug. 14-15 meeting of the baseball owners, at which expansion of the leagues had been expected to be a leading topic, has been cancelled. While the owners concentrate on labor relations, Greater Washington's effort to guarantee purchase by July 31 of at least 10,000 season tickets for its so-far nonexistent team has been going well. It shouldn't flag now, either. That deadline should be kept.

As of late Wednesday, the D.C. Baseball Commission had sold 6,129 ticket packages (starting at $70, the estimated cost for tickets to 10 games). That's a total of about $3.5 million that has been placed in interest-bearing escrow accounts, which is a solid base. Yet if businesses and individual fans don't reach that 10,000 mark as originally promised, other cities competing for teams could get a nasty jump on Washington. Indianapolis, for example, is hustling; its minimum deposit is only $50, but purchases there have hit 11,000.

It may well turn out that an existing team in another city becomes such a financial loser that even its own home town finally lets it go to Washington. But Washington's baseball backers should be prepared to make a run for it, no matter what happens -- delay, expansion or purchase of an existing team.

Money talks, even when the owners can't. Anyone who wants a team here is urged to open a separate interest-bearing account. And this is still very much the month to act.