Paul Krugman (see this for example) seems to think that (i) we can clearly identify "saltwater" and "freshwater" macroeconomists; (ii) the saltwaters are "liberal," i.e. they vote for Democrats; (iii) the freshwaters are conservative, i.e. they vote for Republicans.
First, the saltwater/freshwater distinction, while it could be applied (roughly) in the 1970s, makes no sense today. People and ideas are highly mobile in the economics profession, and ideas grow and mutate. Take Krugman's own department (the economics department at Princeton) for example. We have Alan Blinder, a solid Old Keynesian; Pat Kehoe, who went to Harvard, worked with Tom Sargent, and spent a considerable part of his career at the Minneapolis Fed and the University of Minnesota; Nobu Kiyotaki, who wrote a seminal paper with Blanchard on menu costs, also worked with Randy Wright (a Neil Wallace student), and worked for a time at the University of Minnesota; Chris Sims, also a former Minnesota professor, but a guy who clearly has Keynesian ideas; and Richard Rogerson, who is a Prescott student and Minnesota graduate. Is that a freshwater or saltwater department? Why would you even ask the question? And all those people could easily be Democrats, for all I know.
There might be people out there who are looking for a political party that represents tolerance, a sense of community and shared responsibility, and the judicious use of economic science. That political party does not exist in the United States, so we have to choose the lesser of two evils.
Paul Krugman sees injustice and would like the poor to be better off. He wants to promote the fortunes of the Democratic Party. But dissing "freshwater" economists won't aid in that goal, in part because those animals do not exist. Whatever Krugman says, the 1970s freshwater ideas have been found to be useful, and put to work in any number of ways, even in Krugman's own work. No one can kill a useful idea.
People are generally pretty polite and leave politics out of their casual conversations. But judging from my conversations with people at places Krugman would call "freshwater," there were a lot of Democrats around, maybe even a majority. A prominent 1970s freshwater economist once told me: "There are two people I can't stand. One is the President of the United States, and the other is my brother-in-law." That was during the George W. era. I think that guy would also object to most of what Krugman writes. I think it is good to seek support wherever you can get it. Maybe Krugman is shooting himself in the foot.