Obama to take big step in U.S. Democratic race

By John Whitesides, Political Correspondent

WASHINGTON (Reuters) - Barack Obama will take a major step toward the Democratic presidential nomination when Oregon and Kentucky vote on Tuesday, but rival Hillary Clinton still hopes to spoil the party.

After Tuesday's results, Obama will be able to claim a majority of pledged delegates won in the lengthy state-by-state fight with Clinton.

It is a landmark he hopes will signal the beginning of the end of their grueling race to contest November's presidential election against Republican John McCain.

Voting ends in Kentucky at 7 p.m. EDT (2300 GMT) and Oregon's mail balloting will end at 8 p.m. PDT/11 p.m. EDT (0300 GMT on Wednesday) Results are expected shortly after.

While Obama, an Illinois senator, could still be about 50 to 75 delegates short of the 2,026 needed to win the nomination at the Democratic convention in August, he hopes the milestone will send more undecided superdelegates -- party officials who can back any candidate -- flooding his way.

"A clear majority of elected delegates will send an unmistakable message -- the people have spoken and they are ready for change," Obama campaign manager David Plouffe said in an e-mail message to supporters.

Clinton, who has ignored Obama's almost unassailable lead in delegates for weeks and shrugged off calls to quit the race before the last of the primary elections on June 3, has vowed to keep campaigning.

A newly formed women's political action committee, WomenCount, took out a full page advertisement in Tuesday's New York Times to encourage Clinton, a New York senator, to stay in the race.