I'm quoting TFA.

Sorry, but Cato is definitely a libertarian leaning think tank (one of their few redeeming qualities, in my mind):

- Penn and Teller, the original small l libertarians, are in the board at Cato. That pair wouldn't be caught dead associating with some neocon or populist outfit.

- Cato created and maintain libertarianism.org

- first sentence in Wikipedia's description of Cato: "The Cato Institute is an American libertarian think tank headquartered in Washington, D.C."

We can quibble about the exact political slant of Cato, but it definitely takes policy positions that are more libertarian than mainstream Republican positions. See, for example, the drug war.