Clinton likely to concede at AIPAC meeting on Wednesday

Ickes also conceded that Obama was likely to reach the delegate threshold by Wednesday, and that Clinton would need some time to consider her next step.

He said there was no political significance to a decision to invite staff aides who have worked for Clinton in primary states to either attend her rally on Tuesday night or return home for further instructions. But officials said the aides had been told they would no longer be paid.

"There are no more primaries so there is nowhere to send them," Ickes said.

The former first lady arranged a private meeting with her donors on Tuesday, and was scheduled to address the national conference of the American Israel Public Affairs Committee in Washington on Wednesday.