WITH A DAZZLING, all-star political cast to help deliver the important message, Republican Sen. John W. Warner of Virginia took the case for a complete Metro subway system directly to the new administration the other day and laid it on the lines: By any standards of federal frugality, finishing this 101-mile project is the soundest course that could be taken. To bend the sympathetic if guarded ear of Transportation Secretary Drew Lewis, the senator rallied a broad coalition of Metro believers whose arguments should mean something in a cost-conscious White House.

After all, Harry Byrd Jr. is hardly the voice of devil-may-care largess in Washington -- but he, too, spoke out strongly for going the last miles. "Under no condition," said Mr. Byrd, should the project be abandoned, asking instead that it be "pushed along at the best rate possible." Virginia Gov. John N. Dalton, too, led a chorus, stressing the financial commitments made by, and still to come from, his state government.

The list goes on: From Maryland, there was Rep. Marjorie Holt, stating that transportation is the most serious problem in her district today; Rep. Michael Barnes (D), citing the national interest in the subway system (and its reliance on coal-fueled electricity); Sen. Paul Sarbanes (D), noting that the tracks still to be built are the less expensive sections; from the District, Del. Walter Fauntroy (D) and council member Jerry Moore (R), outlining the role of the city as a partner.

Secretary Lewis does seem to appreciate this exceptional bipartisan support for a model system that has been backed by every president since Eisenhower and all the Congresses as well. "It is clear this is a worthwhile program," Mr. Lewis said.That is encouraging; but it will be the more worthwhile if construction of the full 101 miles for the national capital region can be wrapped up without any enormously costly delays.