The construction firm that built Montgomery County's new courthouse and executive office building in Rockville has filed a $19 million lawsuit against the county, claiming that county mismanagement and political bickering led to delays and massive cost overruns.

Blake Construction Co., Inc. of Washington filed the suit Friday in U.S. District Court in Baltimore. Spokesmen for the county government and the County Council said they could not comment on the suit, since it is pending litigation.

Since the new construction was completed in 1981, Blake and the county have been at loggerheads over which side is responsible for construction delays and for the changes in the complex's design. The issue became political in the heat of last year's election campaigns, with County Executive Charles W. Gilchrist's Republican challenger accusing the incumbent of mismanaging construction of the project.

In the 23-page lawsuit, attorneys for Blake contend that the county "ordered changes in the scope of the work, mismanaged the project, gave plaintiff (Blake) faulty specifications and drawings, failed to provide plaintiff with timely and proper responses."

The suit contends that attorneys for Blake and a county task force had agreed on a $6.2 million settlement last summer but the council refused to fund it.

"Consideration of the merits of the agreement between Blake and the task force was arbitrarily and capriciously subordinated to political conflicts among members of the council, and between the council and the county executive," Blake contends in the lawsuit.

None of the council members has commented publicly about the dispute.