A judge denied the Boston police union's request to block the start of expedited arbitration in the union's contract dispute with the city, clearing the way for the bitter conflict to be resolved before next week's Democratic National Convention (search).

The ruling Tuesday by Superior Court Judge Margaret Hinkle came a day after the state's labor management board, in a sudden reversal, ordered ator Lawrence T. Holden, who was to reach a binding contract settlement by 2 p.m. Thursday and report back to the Joint Labor Management Board.

The Boston Police Patrolmen's Association (search) had filed for an injunction against the decision by the state Joint Labor-Management Committee.

The police union has vowed to picket every convention event attended by Boston Mayor Thomas M. Menino, including the 29 delegation welcoming parties on Sunday. After Monday's decision, union officials said they would step up their efforts and might reconsider their promise not to picket at the FleetCenter, the site of the convention July 26-29.

"We're absolutely going to picket, now more than ever," police union president Thomas Nee said. "It's going to be worse now than it was before because we're calling on everybody. I'm telling you, they're coming in from around the country."

Off-duty officers and police from other cities are expected to do most of the picketing during convention week. Nee predicted a large turnout from union members angered by the board's action.

Menino praised the board's reversal, saying he would abide by the arbitrator's decision, even if the outcome is bad for the city.

"I think finality is coming Thursday at 2 o'clock," said the Democratic mayor, who worked to bring the convention to Boston. "These are very simple issues. What can the city afford?"

Menino brushed aside Nee's threat to go forward with plans to picket convention events. "If there's a contract in place, what are they going to picket?" he said.

The prospect of delegates facing a picket line at convention events worried Democratic leaders. Those from California, Connecticut, Maine, Ohio and Tennessee said Monday they doubted delegates from their states would defy protesting union members. Others sidestepped the problem, saying they believe the dispute will be resolved before delegates arrive.

The police, who have been without a contract for more than two years, are asking for a 17 percent raise over four years. The city is offering 11.9 percent.