Hillary Clinton and Barack Obama’s increasingly destructive nomination fight intensified yesterday amid allegations that the former First Lady was privately telling senior Democrats that her rival is unelectable.

After publicly suggesting last month that John McCain was better-qualified to be commander-in-chief than Mr Obama, Mrs Clinton is now telling Democratic super-delegates that her rival cannot win a general election against the Republican nominee, a claim not fully denied by her advisers.

The latest negative turn came as Mr Obama’s staff announced that he raised more than $40 million (£20 million) last month, including contributions from 218,000 first-time donors. It followed a record $55 million he collected in February. Mrs Clinton’s advisers said that her fundraising total was $20 million.

Mr Obama was also boosted by what appeared to be a wobble by one of Mrs Clinton’s most high-profile supporters. John Corzine, the New Jersey Governor and a super-delegate who backs the former First Lady, said that if she had not won the popular vote by the end of the primary process in June he had the option to shift his support behind her rival. With ten contests left, Mr Obama has a narrow but almost unassailable lead among elected delegates. But neither candidate can reach the 2,024 needed to clinch the nomination, placing the fight in the hands of the party’s 797 superdelegates, the party’s congressmen, senators, governors, former presidents and senior officials who are free to back any candidate.

The Clinton campaign is arguing that if she ends up with fewer pledged delegates, but wins the popular vote, she has just as great a right to the nomination as Mr Obama.

About 250 of the 800 super-delegates have yet to declare their support, although one very high-profile member of the party elite — Jimmy Carter — hinted that he would back Mr Obama. Mr Carter, a Georgian super-delegate, said that Mr Obama won his state’s primary and that his children and grandchildren were behind Mr Obama. Al Gore, another heavyweight super-delegate, has refused to intervene. Mr Obama said on Wednesday that he would have the former vice-president in his cabinet.

George Stephanopoulos, a former senior adviser to Bill Clinton, said that the Clintons were telling super-delegates that Mr Obama could not win the presidency. He said that sources with “direct knowledge” of the conversation between Mrs Clinton and Bill Richardson, the New Mexico Governor who endorsed Mr Obama last month, said the former First Lady told him flatly: “He cannot win, Bill. He cannot win.” Asked at a press conference last night if she told Mr Richardson that Mr Obama could not win, Mrs Clinton said: “I don’t talk about private conversations. But I have consistently made the case that I can win.” Asked if that was a “no”, she said: “That’s a no.”

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