A firm that contracted to supply the windows and doors for the District's new $41 million municipal center has filed for protection from its creditors under Chapter 11 of the federal bankruptcy law, leaving city officials to deal with a bonding company for the building's exterior doors and some other materials.

Dick Janec, project executive for the construction management firm supervising the job, said Ampat/Southern Corp. has completed 98 percent of its work on the building at 14 and U streets NW. He also said the city had withheld enough money from the firm to cover the cost of the unfinished work.

But Janec said the firm's bankruptcy action "will hold things up a little bit more" while the bonding company takes over for the company. "It could be a day, it could be 30 days," Janec said.

District officials have said that Ampat/Southern was partly responsible for long delays in the project, which the city estimates will increase the total cost by $1.5 million. According to officials of the D.C. Department of Public Works, the firm tried to change the design of the windows, delivered the wrong-sized frames and completed the majority of its work 12 months behind schedule.

James Brown, a vice president of Ampat/Southern, has said the firm had "no problems" at the site.

The firm's legal action is the latest setback for a project that has been troubled by design revisions, slow-moving contractors and what several contractors described as the failure of the District's managers to stay on top of the job.