Will the Democrats choose the only candidate who can lose to Donald Trump?

As Hillary Clinton continues to slide, the Democrats will realize they've walked themselves into a corner. Will they try an end run around the primaries by attempting to hijack the convention for, say, Joe Biden? Or accept that they have a choice between Bernie Sanders and Martin O'Malley, the latter of whom will have to be repackaged as the lesser-of-two-goods to make him palatable to the powers that be?