House Speaker Nancy Pelosi tells ABC's "This Week" it would be harmful to the Democratic party if the superdelegate votes overturn what's happened in the primaries and caucuses.

Barack Obama leads Hillary Rodham Clinton by more than 140 pledged delegates. But Clinton has more support than Obama from party leaders who act as superdelegates.

Unless Clinton receives landslide victories in the remaining states, Obama will likely end the primary season with a slight delegate lead, but not enough to win the nomination. That would give the balance of power to the so-called superdelegates — prominent Democrats who are automatically entitled to attend the convention because of their status as members of Congress or other leaders.

More than 500 delegates remain to be picked in primaries beginning on April 22 in Pennsylvania.