May 14 (Bloomberg) -- Hillary Clinton won an overwhelming victory in yesterday's West Virginia primary that did little to cut into Barack Obama's lead in the Democratic presidential race.

Clinton captured 67 percent of the vote and 20 of the state's 28 pledged delegates. She vowed to continue through five remaining primaries, while Obama turned his sights on Republican John McCain.

While Clinton called the result ``a vote of confidence'' in her candidacy, Stephen Wayne, a professor of government at Georgetown University in Washington, said it won't alter the trajectory of her campaign or Obama's.

``Superdelegates are continuing to announce for him,'' Wayne said before the vote. ``Calls for her withdrawal are getting more persistent. The die has been cast.''

Obama has scored a net gain of about three times as many superdelegates in the past two weeks, offsetting Clinton's advantage in West Virginia yesterday.

Obama has won endorsements from 42 Democratic superdelegates since the beginning of the month, including two more today and 29 since last week when he won in North Carolina and narrowly lost Indiana.

By comparison, 10 superdelegates have declared for Clinton since the start of May. After starting the year with twice as many superdelegates as Obama, Clinton now trails the Illinois senator among the party officials and officeholders who get a vote at the national convention. Obama has 286.5 superdelegates to Clinton's 274.5, according to lists and public announcements from both campaigns.

SEC Chairmen

Obama also picked up endorsements today from three former chairmen of the U.S. Securities and Exchange Commission: Democratic appointee Arthur Levitt and Republican appointees William Donaldson and David Ruder. They said Obama is a leader who can ``take us to a stronger and more secure economic future.''

Adding in pledged delegates won in primaries and caucuses, Obama's total delegate count is 1,876.5 to 1,712, according to an unofficial tally by the Associated Press. A candidate needs 2,026 to win the nomination.

With five primaries to go awarding 189 pledged delegates apportioned according to the popular vote, Clinton has almost no chance to catch up, analysts said.

Message Discipline

``Obama has the nomination,'' said James Thurber, director of the Center for Congressional and Presidential Studies at American University in Washington. The only way he could falter is if ``he completely loses his message discipline or an unanticipated scandal occurs.''

The next contests are May 20 in Kentucky, where polls show Clinton with a commanding lead, and Oregon, where Obama is ahead. Primaries also are set for June 1 in Puerto Rico and June 3 in Montana and South Dakota. Clinton last night reiterated that she plans to campaign in every one.

``I am more determined than ever to carry on this campaign until everyone has had a chance to make their voices heard,'' the New York senator told several hundred supporters in Charleston, West Virginia. She had kind words for Obama, telling her audience that even though they were rivals, ``we have always stood together on what is most important.''

Obama limited his appearances in West Virginia as he turned attention to swing states that will be important in the November election against McCain, an Arizona senator who is the presumptive Republican nominee.

Campaigning in Missouri

Obama campaigned yesterday in Cape Girardeau, Missouri, and never mentioned his Democratic rival. He told voters at a manufacturing plant that McCain ``has supported policies that have shifted the burden away from special interests and on to working families.'' He said a vote for McCain is a ``vote for George Bush's third term.''

Today he will be in Michigan, another likely general election battleground. He is keeping his focus on economic issues and pitching his candidacy to working-class voters, a group that has gravitated to Clinton in primaries. Among his stops are a visit to a Chrysler plant in Sterling Heights, a town hall in Warren and an evening rally in Grand Rapids.

Clinton is still pressing for the party to recognize the results of primaries in Florida and Michigan, which were stripped of their delegates by the Democratic National Committee for holding contests earlier than allowed by DNC rules. While she got majorities of the vote in both states, neither candidate campaigned and Obama withdrew his name from the Michigan ballot.

Obama's advisers have rejected any plan that would seat the two delegations as now configured.

Making Her Case

The West Virginia primary gave Clinton a chance to make her case that she has greater appeal to white working-class voters, a group that Obama has had trouble attracting and that she argues is vital to Democrats in the general election.

``The bottom line is this: the White House is won in the swing states and I am winning the swing states,'' Clinton said last night.

By staying in the race, Clinton also can continue to raise money. The New York senator's campaign is $20 million in debt, according to spokesman Howard Wolfson. She and her husband, former President Bill Clinton, have loaned the campaign $11.4 million to keep it going.

Obama has raised $234.8 million through the end of March and had $42.5 million to spend on the primaries.

To contact the reporters on this story: Laura Litvan in Washington at llitvan@bloomberg.net; Karen Leigh in Washington at kleigh@bloomberg.net

Last Updated: May 14, 2008 09:04 EDT