Redskin President Edward Bennett Williams is the prospective buyer with whom Baltimore Orioles principal owner Jerold C. Hoffberger is now negotiating. The sale of the club could come this season, sources said yesterday.

Hoffberger, who is asking $12 million for the team, refused to identify the prospective buyer or characterize the state of negotiations yesterday. Williams declined comment.

Hoffberger's negotiations with the unidentified bidder surfaced Thursday when he told a group of Baltimore businessmen who had finally raised the $12 million that they probably were too late.

According to the Baltimore Sun, Baltimore Mayor William D. Schaefer, who was instrumental in organizing the local group, said Hoffberger told them on Thursday, "It's a little too late. You're a good group, but we're too far down the line (in negotiations with Williams). If nothing comes of it, I'll be back to you."

The mayor also said that Hoffberger had assured him the team would stay in Baltimore, even under a new owner. Hoffberger, however, qualified that statement yesterday.

"The prospective buyer has advised me that one of his first acts will be to tell the people of Baltimore and the mayor that he wants to keep the team in Baltimore and will, unless it becomes economically unfeasible," Hoffberger told The Washington Post.

"No one can or should be asked to make a commitment to keep (the team) in Baltimore if it would not be viable economically," he continued.

For the first time in years, the Orioles may make a modest profit this season. They are leading the American League East and experiencing unprecedented attendance figures, having drawn 897,045 fans for 41 dates - up 245,914 from a year ago. Last month, the club signed a lease binding it to play in Memorial Stadium through the 1980 season.

Their unexpected success at the gate has led to speculation that no sale would be publicly acknowledged during the season for fear of creating a lameduck franchise.

"I might sell before the end of the season. It might be after the end of the season," Hoffberger told the Sun. "It might be before the start of the next season."

It is not known if or how many partners may be involved with Williams, Jack Kent Cooke, Redskin vice president and majority owner, has denied being interested in buying a baseball team.

Former Treasury Secretary William E. Simon was aligned with Williams earlier this year in a big to buy the club. That attempt fell through when Hoffberger said he wanted to give the group of Baltimore businessmen more time to raise the $12 million.

The group formed primarily out of fear that the club would be sold to Washington interests and moved here.

Simon, who said he thought a sale agreement had been reached at the time, angrily withdrew from the negotiations, charging that Hoffberger was "trying to play both ends against the middle." Williams, however, continued sporadic talks with Hoffberger.

The Baltimore group, prodded by Schaefer, scoured the state looking for investors and even turned, unsuccessfully, to the state legislature and city council for loans.

Despite Hoffberger's offer to lend them $4 million to help buy the club from him, the group continually fell $1 to $2 million short of its goal.

Ironically, on Thursday, the group added Towson developer Ralph DeChiaro to its membership and announced that the $12 million had been raised.

But, when they met with Hoffberger to notify him of the development, the mayor said, they learned it might be too late for the group's bid.