Bernie Sanders is going after Hillary Clinton on policies and touting Sanders' encouraging-looking polls as showing his superior "electability."
Clinton and his supporters are going after him on "electability" and specifically his affirmations of "socialism" and the supposed impossibility of getting his proposals enacted.
Although I'm supportive of Sanders over Clinton, I find it hard at this point to get engaged in the polemics. Because Clinton's supporters will vote for Sanders in the general election. And Sanders' supporter will back Clinton in the general.
I'm more concerned about Clinton's attacks on Sanders, though. Particularly her stress on the need for a more hawkish foreign policy than what Sanders is advocating. And we need a drastic change in the general foreign policy orientation of the US. We need to get away from the evil Bobbsey Twins, neoconservatism and liberal interventionism.
Robert Perry describes her approach on foreign policy vs. Sanders in Robert Parry in Hillary Clinton Seeks Neocon Shelter Consortium News 01/22/2016.
Also, by emphasizing her centrism against Bernie's progressivism, she widens the opening for a potential centrist spoiler campaign by the Republicans, e.g., by Michael Bloomberg.
It's also, well, impractical to think that Clinton's pragmatic contrast Sanders and later to the Republican nominee is going to make her proposals easier to enact as long as the Republicans control either House of Congress. And Clinton running on the chronic Democratic fear of sounding like a Democrat is not the optimum approach to getting a Democratic Congress elected or building a mandate for actual Democratic positions.
Charlie Pierce reminds us of the depth of the problem with either Congressional House under Republican control in The Dreadful Truth That Unites Hillary and Bernie Esquire Politics Blog 01/20/2016.