Barack Obama drew his biggest cheers of the night when he vowed to help Hillary Clinton pay off her campaign debt. The pooler was ushered out of the meeting room where about 200 of Clinton's top donors -- those who had raised a combined $230m -- had gathered to watch the Democratic nominee try to build a bridge.

But a few minutes later, a few, less happy donors asked pointed questions. According to someone in the room, one Clinton donor asked Obama directly whether he was going to add her to the ticket as his vice presidential nominee. Even Sen. Clinton looked uncomfortable, gesturing to Obama to move on, which he did.

A second question was edgy: would Obama accept a roll call vote at the convention? Obama responded judiciously, according to the participant, saying, "Hillary and I are going to negotiate this thing and talk about it, and obviously we're going to do what is right for the party. We're all going to make sure we agree."

Several donors took the occasion to speak to Obama. Lanny Davis, a vociferous Clinton defender on television, introduced himself to Obama, who responded, "I know who you are." Davis fidgeted. But he thanked Obama because he son felt for the first time invested in politics. But Obama had to understand: he's known Hillary before she was a Clinton. "I don't want you to take out of context what I said during the campaign," he told Obama.

The mood? "Guarded optimism," according to an attendee.

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