Scott C. Humphrey, former president of the Alexandria Chamber of Commerce and a longtime city businessman, has been selected to fill a vacancy on the City Council, a move that surprised many political insiders and angered some leaders in the dominant Democratic Party.

Circuit Judge Donald H. Kent appointed Humphrey, 58, a real estate appraiser and broker, to serve through June 30, a time during which the council is expected to confront major development and budget issues.

"This is a big job," said Humphrey, a Democrat who fills the vacancy created by the resignation of Mayor James P. Moran Jr., who was elected to Congress. "But I don't consider myself a slow learner, and I will work hard to prepare myself to make prudent decisions that I hope will be in the best interest of the city."

Although Humphrey is a Democrat, some Democratic leaders are less than enthusiastic about his appointment, saying he is a political unknown who has not been active in party politics. However, the appointment pleased Republicans and business leaders. Neither party nominated him for the vacancy.

"I'm delighted that the judge chose someone who has strong roots in the Alexandria business community and someone who will bring a business perspective to council," said Michael Holm, city Republican Party chairman. G. Barton Middleton, president of the Alexandria Chamber of Commerce, said Humphrey "will bring a balance to council."

However, Michael Reid, city Democratic Party chairman, expressed concern that Kent was attempting to change the character of the council. Reid said he does not know where Humphrey stands on issues. "I don't even know who he is," he said. Reid, who described his feelings as those of "indignation," said he was considering an attempt to change the city's charter that allows a judge to fill a vacancy on the council.

Under the charter, Kent, as the chief circuit judge, has the authority to fill the vacancy because Moran resigned less than 180 days before the next scheduled council election, allowing the city to avoid a special election.

As word of Humphrey's selection circulated throughout the city yesterday, political players began to do their own background work on him. Several sources questioned whether Humphrey's work in appraising may create conflicts of interest with council business. The sources specifically cited Potomac Yard, a pending major development, and hotly contested plans for a city parking lot.

Humphrey, an Alexandria native and chairman of the board of the Bank of Alexandria, said his past work probably would not allow him to vote on the parking lot proposal. His work dealing with Potomac Yard had been limited and may not preclude him from voting on that matter, he said.