I hate this cable news brain saying. Nobody has that much allegiance to a "party" and concepts of "country" or "national interest" are too vague and abused to be meaningless, and in practice are usually closer to "what's good for General Motors is good for America" than "wow what if people didn't worry about paying for cancer treatment for their kids."
Mitch McConnell doesn't put "party over country," he uses political power to get what he wants in ways some people find distasteful and other people cheer.
If people are bad it isn't because of party allegiance. They might be concerned with their individual fortune as it is linked to various things, but nobody cares about The Party. They're bad people who are using and maybe abusing power. This is dumb.
...adding that this is just another version of "The problem with Washington is TOO MUCH PARTISANSHIP" which is about 3 centimeters away from "The problem with Washington is TOO MUCH DEMOCRACY." Bad people who are bad is the problem.