WASHINGTON – For all their delight in soaring voter registration and strong poll numbers, some Democrats fear the contest between Sens. Barack Obama and Hillary Rodham Clinton might have a nightmarish end, which could wreck a promising election year.

The chief worry is that Clinton may carry her recent winning streak into Pennsylvania, Indiana, North Carolina and other states, leaving her with unquestioned momentum but fewer pledged delegates than Obama. Party leaders then would face a wrenching choice: Steer the nomination to a fading Obama, even as signs suggested Clinton could be the stronger candidate in November; or go with the surging Clinton and risk infuriating Obama’s supporters, especially blacks, the Democratic Party’s most loyal base.