Amtrak president Alan S. Boyd said yesterday he will seek congressional support and the cooperation of federal agencies for a plan to develop Union Station commercially and turn it into a complex of shops, restaurants and entertainment facilities.

Boyd said he would ask for federal financing for the restoration of Union Station as a historic landmark and would ask the Department of Transportation and the Department of the Interior to step to the side and assign Amtrak to coordinate the venture and to hire a private developer.

For several months Amtrak has been pushing the notion of commercial development of the train station -- turning it into a mall to operate side-by-side with the train station and the visitors center already there. The idea was endorsed in June by a panel of the Urban Land Institute, a nonprofit organization that brings in groups of land-use specialists to consider development problems.

Among ULY's recommendations was a call to centralize management of the train station -- currently parceled out among Amtrak, DOT and Interio -- and to get the government to accept the notion that renovating the buildings is a federal responsibility.

The ULI study estimated that the Union station complex could serve approximately 18,000 rail passengers a day as well as 14 to 16 million visitors to Washington each year and some 70,000 office workers whose jobs are nearby. Although the panel offered no estimates of earnings or other figures to support the conclusion, it predicted that a commercial complex could bring in enough revenue to cover its own costs and to defray part of the $3.5 million annual rent the federal government pays for the building.

Turning Amtrak's hopes for Union Station into reality, however, would require a number of steps, including congressional approval of a bill to amend the National Visitor Center Facilities Act to transfer the rail station from a temporary space behind the building into the main concourse. Action on that bill is still pending.

It would also require resolution of some sticky questions: whether intercity bus terminals such as Greyhound and Continental should be part of the complex and what to do about parking.