According to the Senate Finance Committee report on Daschle: “Senator Daschle told staff that in June, 2008, something made him think that the car service might be taxable and he disclosed the arrangement to his accountant.” It was on June 3, 2008, that Obama—whom Daschle had endorsed—clinched the Democratic nomination. Might that “something” that made Daschle think about tending to his tax problem have been his lust for power? And isn’t it telling that he didn’t fix the problem until after his selection as HHS secretary?
Any Republican nominee who tried to maintain his nomination under such circumstances would be laughed out of town.
Update: Immediately after Obama clinched the Democratic nomination, Daschle was making it known that he “might relish serving as HHS secretary”, as this June 5 National Journal article reports.