The power-to-responsibilty ratio is astonishingly high for a US Senator. John McCain, for example, fought many times harder against J.D. Hayworth to keep his seat in the Senate than he ever did against Barack Obama in their race for the Presidency.
My point—which I failed to note—is that Bernie Sanders would need a lot more incentive to drop out of the race. At the very least, Bernie’s race will help him keep his seat in the Senate.