President Lyndon B. Johnson is often used as evidence that a sufficiently persuasive president can force Congress to do what he wants. But it turns out Johnson wasn’t a big fan of the great-man theory of presidential bullying. The fourth volume of Robert Caro’s biography quotes Johnson explaining to his aides why they couldn’t steamroll Sen. Robert Byrd (D-W.V.):
They seemed to feel there were alternatives to giving Byrd what he wanted, he told the six economic advisers; there weren’t, and he gave them a lesson in political realities. You couldn’t get around the Senate, he said, telling them about a President, a President at the very height of his popularity, who had tried it, attempting in 1938 to unseat southern conservative senators by going into their states to campaign against them. “Of course, you could try to take it to the country. FDR tried that, with his tremendous majority, and got licked,” he said. “It wouldn’t work” if they tried it now, either.
And the Senate has gotten a lot harder to manage since then.