Although considered Founding Fathers of the United States, Thomas Jefferson and John Adams did not sign the Constitution. They were serving as U.S. ministers overseas and did not attend the Constitutional Convention.
Q: Is Sen. Ted Cruz, who was born in Canada, eligible to be the U.S. president? A: Most likely. The legal consensus is that Cruz qualifies because he was born to a U.S. citizen living abroad, making him a U.S. citizen at birth.