unforced error
1). In tennis, whenever a player misses an otherwise easy or effortless shot due to their own inattentiveness rather than the opposing player's skill.

2.) In politics, a polite term for when someone ends up creating their own scandal through poor or tactless decision making.
1.) Bobby Sands failing to make that save at Wimbledon was an unforced error.

2.) Donald's Trump's statement about Mexican migrants "bringing in drugs" and being "rapists" during the 2016 campaign was an unforced error that cast a cloud over his entire presidency.