I don't particularly agree with Ezra Klein or Francis Fukuyama, often vehemently disagree. But on the latest episode of Klein's NYT show it was interesting to hear Francis mention this coupling of wealth and political power being one of the core problems the US is grappling with.

Separate the nouveau robber barons from political power like we did the clergy?

In the United States, clergy never had formal political power. Religious movements did play major roles in the abolition of slavery and Prohibition of alcohol.

The United States had campaign-finance laws to limit the political influence money can buy. The McCain–Feingold Act restricted “dark money”. The Supreme Court struck it down in Citizens United v. FEC.