In the U.S. if you run for President and lose, you don't run for President again. At least as a Democrat or a Republican.
Nixon was the last guy to pull off that move, after waiting a cycle.
In Mexico, AMLO just barely lost, again. I don't know if another PD/PT Candidate could have won there, but it might be worth trying to avoid putting the same loser up over and over....
McGovern lost the nomination in 1984. He got 3rd place in Iowa. The Democrats decided it was time for a new 49 state loser.
Bush didn't have a real win in 2000, but ran again in 2004.
William Jennings Bryan probably finds this thread hilarious.
Honorable mention to FDR. Let's see. You're a Democrat running for VP, and you lose your home state of New York by 40 points? Well, clearly you're destined to win the Presidency 4 times after you get polio.
