No he isn't killing the D's with some crazy far left agenda. That is just silly and really uneducated.
The D's are killing themselves by being wishy washy OR they are just proving themselves to be just the same as the R's with the whole wanting stay in power thing.
The D's had an opportunity to craft meaningful financial and healthcare legislation that would help the middle class for years to come but ended up simply wussing out to the powerful lobbies in Washington. Far left has little to do with it.
Edit.
I don't understand how you can think that. Maybe I am missing something and you can educate me on how the D party is being destroyed by Obama's far left policies.