If baseball is going to return to Washington, it became apparent yesterday the area will have to win a crowded expansion race -- not an auction for the Montreal Expos.

Several hours after at least 18 groups submitted applications to the NL Expansion Committee, Expos owner Charles Bronfman indicated he will continue to spurn U.S. offers for his team because he is "encouraged" a local group will purchase it and keep it in Montreal.

But because a sale has not been completed, Washington developer John Akridge said he still would attempt to contact Bronfman this week about purchasing the Expos. Bronfman had said if local interests did not come forward by Sept. 1, he would begin entertaining offers from U.S. interests.

"We wanted to know by this time whether there was sufficient interest by local people to have a local {buyer} group. We believe there is," Bronfman said at a news conference following a meeting he had with the club's board of directors and Expos President Claude Brochu, the person Bronfman has designated to find local investors. "We're pretty darned encouraged that the team will stay in Montreal and be sold locally."

Asked if this meant he would continue offering the Expos only to local interests, Bronfman replied: "Things are looking good. So we'll just continue the course we're pursuing until it comes to fruition."

A group of Montreal credit unions called Les Caisses Populaires Desjardins announced yesterday it is willing to invest $5 million in the Expos.

Akridge was undaunted, but realistic.

"The possibilities are sounding more and more remote," he said, "but I still think it's worth making a phone call."

At least 17 groups representing a total of 10 cities and one group with the unique hope of representing several cities submitted a reponse to the NL Expansion Committee's questionnaire and a $100,000 deposit on the $95 million entry fee.

The league office declined to say how many groups or cities met yesterday's noon deadline, pending initial examination of the applications by the committee. Douglas Danforth of the Pittsburgh Pirates chairs the group, whose other members are NL President Bill White, Fred Wilpon of the New York Mets and John McMullen of the Houston Astros. They are scheduled to meet today in New York, NL spokeswoman Katy Feeney said.

The committee is scheduled to announce a short list of finalists by the end of the year and award the teams by Sept. 30, 1991.

Akridge's group, which would like to permanently locate a team at RFK Stadium, filed its application. So did the Mark Tracz-led group that wants to initially put a team at RFK Stadium, then move to a new facility in Northern Virginia. Tracz's group, which is considering building its stadium in Loudoun County, received a resolution of support late Tuesday night from the Loudoun County Board of Supervisors.

A survey of other groups and cities known to have requested questionnaires found Miami and Tampa-St. Petersburg each represented by three groups, Denver and Phoenix each by two groups and Buffalo, Charlotte, Nashville, Orlando and Sacramento each by one.

A group from Boynton Beach, Fla., identifying itself as America's Baseball Team Inc., announced it had applied with the intention of dividing its home games among four of the following five cities: Washington, Buffalo, Denver, Miami and Tampa-St. Petersburg. It said it assumes the fifth city will be the one awarded the other expansion team. A spokesman for the group said it had contacted RFK Stadium officials and unidentified potential backers in the Washington area.

Groups representing Vancouver and New Orleans that had requested questionnaires could not find prospective owners, officials in those cities said.

Orlando's group underwent a major change. It announced Richard DeVos, co-founder of the Ada, Mich.-based Amway Corp., has replaced NBA Orlando Magic owner William duPont as its principal financial backer.

Buffalo's principal financial backer, Bob Rich Jr., announced his group's other investors. They include Washington-based national radio-TV talk show host Larry King.