WASHINGTON — An exhausted Senate gave pre-dawn approval Saturday to a Democratic $3.7 trillion budget for next year that embraces nearly $1 trillion in tax increases over the coming decade but shelters domestic programs targeted for cuts by House Republicans.While their victory was by a razor-thin 50-49, the vote let Democrats tout their priorities. Yet it doesn't resolve the deep differences the two parties have over deficits and the size of government.Joining all Republicans voting no were four Democrats who face re-election next year in potentially difficult races: Sens. Max Baucus of Montana, Mark Begich of Alaska, Kay Hagan of...