President Clinton summoned players and owners to the Oval Office tonight after a federal mediator failed to solve the 179-day-old baseball strike. "The President was exasperated," said White House spokesman Mike McCurry. The national pastime drew attention from both ends of Pennsylvania Avenue. With spring training slated to start next week, Senate Majority Leader Bob Dole--speaking on the Senate floor this morning--urged both sides to accept mediator W.J. Usery's proposed solution. But neither Dole nor House Speaker Newt Gingrich want Congress directly involved.