Senator Hillary Clinton has vowed to fight on in the Democratic nomination race after loaning her own campaign $6.4 million (€4.1 million).
Senator Barack Obama's big win in North Carolina and Mrs Clinton's slim victory in Indiana widened his advantage in their battle for the right to face Republican John McCain in the November presidential election with just six contests remaining.
The results left the cash-strapped Clinton campaign with little chance to halt Mr Obama's march to the nomination. But the New York senator brushed off calls to drop out of the race.
Democratic presidential candidate Hillary Clinton campaigns in Shepherdstown, West Virginia
"I'm staying in this race until there is a nominee," Mrs Clinton told reporters after a campaign rally in Shepherdstown, West Virginia, which holds a primary next week.
At a Washington fundraising event to honour women, she said she had been counted out before. "I am staying in this race," she said. "Too many people have fought too hard to see a woman continue in this race."
Mrs Clinton dipped into her personal fortune again to try to keep pace with Mr Obama, putting $5 million into her campaign in April and $1.4 million over the past week, aides said.
"It's a sign of my commitment to this campaign," Mrs Clinton said of the loans.
She vowed to fight on to contests in West Virginia, and in Oregon and Kentucky on May 20th, but Obama aides said he was closing in on the nomination.
With just 217 delegates at stake in the final six contests, Mrs Clinton has no realistic chance to overtake Mr Obama's lead in pledged delegates who will help pick the nominee at the August convention. It is also nearly impossible to catch him in popular votes won in the state-by-state battle for the nomination that began in January.
But neither can win without help from superdelegates - nearly 800 party insiders and officials who are free to back any candidate. More than 250 superdelegates remain uncommitted.