Despite urging from the candidate himself, Barack Obama's big campaign donors are not rushing to help Hillary Clinton retire her $20 million debt:

As Mr. Obama and Mrs. Clinton prepare for their first joint fund-raisers to benefit the Obama campaign, in New York City on Wednesday and Thursday, their two camps are straining under the weight of continued resentments, recriminations and feelings that remain raw since the long primary battle.

Mr. Obama has asked his top donors to help raise money for her debt, and so far they have come up with less than $100,000 (though more in pledges), Clinton campaign officials said - a "paltry sum," in the words of one.

Several Obama donors said in interviews that they were balking at Mr. Obama's call for help because they believed Mrs. Clinton accumulated most of her debts after she had lost any mathematical chance of winning the nomination and was hanging on only in hopes of an Obama collapse. The idea of helping her now - and lining the pockets of Mr. Penn, a reviled figure in the Obama camp - is galling to them, they said, especially at a time when they say any available money should go to defeating Senator John McCain and the Republicans in November.