On net the American people don’t like either major party at the moment but they dislike Democrats the least. From Gallup:

Republican and Democratic Party Net Favorable Ratings, 1992-2014

Having a net favorable rating of negative 6 normally won’t be considered much of an accomplishment but in a two party system politics is a zero-sum game. Being dislike noticeably less than the other guy is sadly almost as good as being actually popular.

The generic ballot polling is still the most telling number and at this point the parties are effectively tied, but this favorable poll points to a potential avenue of attack for Democrats this November. In certain districts nationalizing the race could help.

After all we have entered an era of significant party unity in Congress when it comes time to cast votes. The stances of individual members matter less than a few decades ago as the overall position of the party has become more determinative.