NOT MY UNICORN RIDER:

Another senior Democrat who advises the White House, speaking on the condition of anonymity because of the sensitivity of the matter, said the current feeling among Obama and his aides is "exasperation."

"He doesn't think they have any reason to run away from him," the adviser said. "He thinks there is a strong message there."

The president has hinted at the tension in recent remarks. "Make no mistake, these policies are on the ballot, every single one of them," Obama said earlier this month. He restated the obvious a few weeks later in a radio interview when he said of the Democratic senators who are struggling this year: "The bottom line is . . . these are all folks who vote with me; they have supported my agenda in Congress."

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