Which politician, upon retiring from office, said that he had "only two regrets: that I have not shot Henry Clay, or hanged John C. Calhoun."?

Andrew "Old Hickory" Jackson

Correct, Miles ! Who else could have possibly said something like that? And meant it!
Thanks for the answer !

I believe he was the only American President to participate in duels and having, on one occasion, to kill his adversary.