Warren is a tool to divide the base. She didn't go to Dakota when it was needed, stayed out of 2016 for fear of angering Clinton, didn't support M4A till every other presidential candidate did & is seemingly open to more moderate ways. She has also said she doesn't rule out PAC money for the GE.
Add to the fact that has poor temperament & massive electability concerns. How is cop Kamala Harris any worse than Warren? Apart from achieving nothing, Warren cant even get elected. And someone with 0 political courage is a failure.
Stuff like this is why I'd vote for Biden over Sanders if it came down to it.