It’s only happened once. Two future presidents — both allies and friends of Thomas Jefferson — running against each other for one seat in the U.S. Congress. Of course, I’m talking about the 1789 campaign between James Madison and James Monroe.

Author Chris DeRose’s new book, “Founding Rivals: Madison vs. Monroe, the Bill of Rights, and the Election That Saved a Nation,” examines how this very close race impacted the Constitution and the Bill of Rights, and argues that the Bill of Rights would never have survived the First Congress had Monroe won in 1789 (just as “only Nixon could go to China,” DeRose argues that only Madision could have effectively championed the Bill of Rights.)

You can listen to a streaming version of my full conversation with DeRose here. Or download the podcast on iTunes.