It wasn't the Ricky Williams draft pick swap, or even the questionable ESPN magazine cover shot with Williams.
It wasn't starting Doug Flutie in the 1986 NFL playoffs.
It wasn't even neglecting to let Walter Payton score a touchdown in Super Bowl XX.
“Biggest mistake I’ve ever made,” Ditka said last week iat oil company Canary's grand opening ceremony in North Dakota, according to the Dickinson Press.
“Not that I would have won, but I probably would have and he wouldn’t be in the White House.”
We obviously know the answer to that now, but would he have won?
The Atlantic Wire report takes a look back at that 2004 race, using results from SurveyUSA. When asked who they'd vote for if the election were held that day with only candidates being Mike Ditka and Barack Obama, 51% of respondents said they'd vote for Obama, with 44% saying they'd vote for Ditka, and 4% undecided.
So, not exactly a probable win.
Ditka eventually decided not to run, citing previous commitments and obligations, including working as an ESPN football analyst and running his steakhouse in Chicago.
Obama, an Illinois state senator at the time, handily defeated opponent Alan Keyes, who was chosen to replace original nominee Jack Ryan. Ryan withdrew from the race after a sex club scandal involving ex-wife Jeri Ryan became public.