We've heard "it takes 60 votes to get anything done in the Senate" so many times over the last several years, much of the political world has more or less internalized the argument. Requiring supermajorities on everything has slowly become routine, and it rarely occurs to the establishment and those who cover it to question the dramatic shift.

With that in mind, Ezra Klein posts a copy of this fascinating letter from the LBJ presidential library, sent in by Yale student David Broockman. It shows correspondence from Mike Manatos, Johnson's Senate liaison...

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