Directors of the Greater Washington Board of Trade yesterday elected Peter F. O'Malley, a politically powerful Prince George's County lawyer, president of the organization for 1986.

O'Malley, 46, was selected to head the business organization following the unexpected resignation of Luther H. Hodges Jr. as president-elect.

Hodges is the second official to resign as president-elect of the Board of Trade in just over two weeks. Earlier this month, Roger R. Blunt, the president of one of the area's largest black-owned construction firms, announced his resignation as president-elect of the board shortly after his firm filed for bankruptcy.

Like Blunt, Hodges, who is chairman and chief executive officer of Washington Bancorporation, said he decided to decline the office because he needs to devote more time to his company.

Washington Bancorporation and its principal subsidiary, National Bank of Washington, were sold recently by the United Mineworkers of America to Colson Inc., an investor group headed by New York interests. The sale has been approved by the Federal Reserve Board but also must be sanctioned by the Justice Department and the Comptroller of the Currency.

"I just concluded that with the closing of the contract to acquire the UMW shares, with a whole new set of owners and with the changes that are taking place in the banking industry, I could not devote as much time as I would like to the Board of Trade," Hodges said yesterday.

If Blunt had not resigned, Hodges would have been president-elect in 1986. "That would have been reasonable," said Hodges, "but being president was something that would have taken too much time from the bank."

Hodges currently is president of the Washington-Baltimore Regional Association, an organization formed by business leaders in the two cities to promote economic development in the region.

O'Malley will succeed Julia M. Walsh as president of the Board of Trade on Jan. 1.

O'Malley,a partner in the Upper Marlboro law firm of O'Malley Miles McCarthy Harrell and Levine, has been a director of the Board of Trade since 1982. His election underscores the Board of Trade's recent emphasis on being the principal voice of business in the region and not just in the District.