People will excuse someone they like. They won't excuse someone they don't like. The action can be exactly the same thing.

Apparently, it's part of the office.

Kennedy: The Soviet Union has more nuclear missiles than the U.S.
Johnson: We still seek no wider war.
Nixon: I am not a crook.
Ford: I restored decency and trust to the Presidency. (HA!)
Carter: I am a nuclear physicist and a peanut farmer (he was neither)
Reagan: I do not recall.
Bush 41: Read my lips, no new taxes.
Clinton: I did not have sexual relations with that woman.
Bush 43: We found the weapons of mass destruction.
Obama: Everyone will get a $2500 decrease in their health insurance premiums and get to keep their doctor.
Trump: I have the highest polling numbers in the history of the Republican Party.