This is very reminiscent of Gore Vidal’s quote, which happens to make a better case imo:

There is only one party in the United States, the Property Party … and it has two right wings: Republican and Democrat.

Republicans are a bit stupider, more rigid, more doctrinaire in their laissez-faire capitalism than the Democrats, who are cuter, prettier, a bit more corrupt — until recently … and more willing than the Republicans to make small adjustments when the poor, the black, the anti-imperialists get out of hand. But, essentially, there is no difference between the two parties