Remember, the DNC (and RNC) are much more interested in House and Senate races than the presidency.
Presidents come and go, but Senators can last 30 years, and they control the purse strings.
If DNC has a choice of bscking Obama and losing Senate... or throwing him overboard and retaining Senate, it’s Bye, Bye, Barack!
That is correct! The real power is in the House and Senate, they are the engine!