Hillary Rodham Clinton, defying electoral math stacked against her, is urging supporters to ignore predictions that her White House bid was over. Barack Obama, meanwhile, was reaching out to top Democrats who could help seal a historic nomination well within his grasp. Clinton spent some of Thursday in West Virginia - the next battleground and where she is favored to win - telling supporters that she had faced similar pressure to withdraw before she went on to win New Hampshire, Ohio, Texas and Pennsylvania's primaries. "I'm running to be president of all 50 states," Clinton said to cheers. "I think we ought to keep this going so the people of West Virginia's voices are heard." But, smarting from a crushing loss in North Carolina and a narrower-than-expected win in Indiana on Tuesday, the former first lady also sought to stave off further defections among long-time supporters who saw the pace of the race decisively in Obama's favor. Obama, on the cusp of making history with his bid to be the US's first black president, made an impromptu appearance in the US House of Representatives on Thursday. It marked his latest effort to woo Congressional superdelegates since Tuesday's contests, which positioned him within striking distance of the party's White House nod in a race that has polarized Democratic voters and raised concerns about unity ahead of the November presidential election.