It might be what "should" be done but given the election results last night I'm not sure it's a winning recipe for electoral success. A big part of the country is not down with pulling harder to the left.
There are different axes of "left"-ness at play here. A large portion of the country doesn't like hearing about how urban liberals are the only moral human beings on the planet. Much the same portion of the country wants their goddamned labor unions back.