Hillary Clinton dismissed pressure to end her campaign for the Democratic presidential nomination after securing an overwhelming win in Tuesday's West Virginia primary, declaring "this race isn't over yet."

Democratic presidential hopeful Hillary Clinton greets people at a farmer's market on Tuesday during a campaign stop on West Virginia. (Elise Amendola/Associated Press) But the victory failed to affect the significant delegate lead held by her rival, Barack Obama.

With 95 per cent of polls reporting, Clinton had taken 67 per cent of ballots cast in the state, compared to Obama's 26 per cent. Clinton added 20 delegates and Obama won eight, according to an analysis of election returns by the Associated Press.

During her address Tuesday night to supporters in Charleston, the New York senator referred to the growing chorus calling on her to withdraw from the contest, reiterating that she was staying in the race because she believes she is "the strongest candidate."

"I'm more determined than ever to carry on this campaign until everyone has had a chance to make their voices heard," she said amid chants of "Hillary" from the throng of supporters.

"There are some who have wanted to cut this race short, but here in West Virginia, you know a thing or two about rough roads to the top of the mountain."

The predominantly white, working-class state was among the last half-dozen states to take part in the hotly contested race between Clinton and Obama.

The surging senator from Illinois holds a near-unassailable lead among delegates who will choose the party's presidential nominee at the Democratic National Convention in August in Denver.

Tuesday's primary left Obama with a 166.5-delegate lead, with 1,883.5 delegates, including endorsements from party and elected officials known as superdelegates, while Clinton has 1,717, according to an Associated Press tally.

Obama now leads in states won, pledged delegates won in primaries and caucuses, and superdelegates.

Obama made just one visit to the state on the last day of campaigning Monday before moving on to Missouri, a state that will be crucial in the presidential race against Republican party candidate John McCain in November's general election.

Obama talks patriotism

With patriotism expected to be a presidential campaign theme as Republicans contrast McCain's years as a prisoner of war in Vietnam and his decades of service in Washington with Obama's youth and inexperience, the Illinois senator talked about love of country and the need to help veterans of wars in Iraq and in Afghanistan.

"At a time when we're facing the largest homecoming since the Second World War, the true test of our patriotism is whether we will serve our returning heroes as well as they served us," he said.

Political observers and campaign insiders say Obama's delegate lead makes it mathematically impossible for Clinton to get the nomination, even if she wins all the remaining primaries. Obama is ahead in the overall delegate count, with 1,869 compared to Clinton's 1,697.

Instead, she'll have to convince superdelegates to the August nominating convention that her opponent's support among white, working-class voters is soft, a weakness the Republicans could exploit.

Her campaign is also deeply in debt, while Obama's coffers are overflowing.

Whatever the outcome of the latest primaries, CBC's Henry Champ, in Charleston, W.Va., said many believe it's just a matter of time before Clinton withdraws from the race.

"For Obama, this race is over," Champ said Tuesday. "The focus is now on John McCain, and the Obama campaign is making it clear this is now a two-man race for the White House."

Current polling suggests that either Democratic candidate would have a slight edge on McCain in the election, but analysts warn that voting is still too far off to make accurate predictions now.

With files from the Associated Press