"Once
upon a time Republicans were tax collectors for the welfare state. Now
Democrats are the austerians of reactionary Keynesianism." – Corey Robin
There's a lot going on in that quote, so if you want to understand it, I recommend Robin's essay at Crooked Timber. It's pretty in-depth – but a good historical analysis of the way the Republicans and Democrats have evolved over the last several generations, such that modern Democrats more closely resemble Republicans of 50 years ago than they do historical Democrats. And not to everyone's benefit.