Reply #4: No

[Fovea]

Then when things fall apart in a horrible way, the Dems are as much to blame.

If you want to make the Greens the only progressive party, sure. But this ploy will hurt the Dems far more than being an oppositions party.
We will be hard pressed to stop much as it is, but that does not mean the dems should not resist.

As a former Dem, I think resistance is the only thing that might get them back as a unified party, instead of a bunch of mice.