The returns weren't all in yet on Tuesday's Republican primaries but President Obama didn't wait. He kicked off his 2012 campaign against Mitt Romney with a hard-hitting speech centered on the House Republicans' budget plan -- which Romney has enthusiastically endorsed.

That plan, by the way, is the most radical reverse-Robin Hood proposal propounded by any political party in modern America. It would save millionaires at least $150,000 a year in taxes while gutting Medicaid, Medicare, food stamps, transportation, child nutrition, college aid, and almost everything else average and lower-income Americans depend on.

Here's what the president had to say about it:

"Disguised as a deficit reduction... it is really an attempt to impose a radical vision on our country. It is thinly veiled social Darwinism."

We are likely to hear a lot more about social Darwinism in the months ahead. It was the conservative creed during the late 19th century -- legitimizing a politics in which the lackeys of robber barons deposited sacks of money on legislators' desks, and justifying an economy in which sweat shops were common, urban slums festered, and a significant portion of America was impoverished.

Social Darwinism encapsulated the idea of survival of the fittest (a phrase Charles Darwin never actually used) as applied to societies as a whole. Its chief apostle in America was Yale Professor William Graham Sumner.

Here's what Sumner had to say in his social-Darwinian classic What Social Classes Owe to Each Other (1883):

Let it be understood that we cannot go outside of this alternative: Liberty, inequality, survival of the fittest; not-liberty, equality, survival of the unfittest. The former carries society forward and favors all its best members; the latter carries society downwards and favors all its worst members.

Could there be a better summary of what today's regressive Republicans believe?

Robert Reich is the author of Aftershock: The Next Economy and America's Future, now in bookstores. This post originally appeared at RobertReich.org.