Democratic elected officials support corporate welfare so much that they exceed even Republican elected officials on that score.
One reason: Democrats are fonder of big government, and big government is a necessary ingredient in corporate welfare. Another reason is an asymmetry in the political landscape.
Currently, the grassroots Right (the Tea Party, you could say) applies serious pressure to the GOP to oppose corporate welfare. This pressure is a counterweight to the influence the GOP's corporate donors have on the party. See Dave Brat's victory over Eric Cantor, followed immediately by Kevin McCarthy's conversion on the Export-Import Bank. See Club for Growth and Heritage Action opposing the Export-Import Bank and the ethanol mandate.
The grassroots Left, on the other hand, is far quieter on the question of corporate welfare. Zephyr Teachout in New York is challenging Democratic Gov. Andrew Cuomo on related issues, but it's not a priority for the Left — or maybe folks on the Left are unwilling to be seen on the same side of an issue as those crazy Tea Partiers.
Ralph Nader has issued a call for a Left-Right alliance against corporatism. In many cases, that would involve the Left joining the fights already being fought by the likes of the Club for Growth and Heritage Action. In at least one case, though, the Left is leading this charge. Trying to rein in corporate welfare from states to a Tesla battery factory.
A half-dozen groups, including the Progressive Leadership Alliance of Nevada, have drafted an open letter to various states about Tesla Motors as it decides where to locate a battery "gigafactory," urging negotiators to be transparent and not to give away the store.
Of course, I would go further: Why not make sure Tesla gets no special treatment? If any policy is needed to lure Tesla, let it be a policy that applies to all businesses in the state. But this is a good start.
P.S. The irony is that the Left was also very solid in opposing cronyism that hurt Tesla, when the car dealers were trying to use regulation to keep Tesla from selling cars in its own showrooms.