Barack Obama

Here's what often happens: The President proposes something. The Congressional leadership of his party honors party loyalty and supports "their" President. The Congressional leadership of the other major party works out their own position. Sometimes there's a vote on a bill that's pretty much what one side wanted, but often what finally emerges is some kind of compromise.

In that scenario, Sanders and Warren have the option of supporting the Obama position, the McConnell/Boehner position, or a compromise. Nothing else is on the table -- because Obama didn't use his office to put anything else on the table.

The President proposes something. The Congressional leadership of his party writes the enabling legislation to the Left of the President's proposal. The Congressional leadership of the other major party works out their own position. Sometimes there's a vote on a bill that's pretty much what one side wanted, but often what finally emerges is some kind of compromise. And the compromise would be found somewhere between the position of the President and that of his Party leadership ... but certainly to the left of negotiation between the President and the opposition party's position.