The prime minister, who was taking questions from Asda staff at a headquarters in Leeds, was asked what his worst fear about the upcoming general election was.
After explaining he was most afraid of an SNP government backing up a Labour government, he meant to say next week's election was "country-defining" – but instead made an embarrassing mistake.
"This is a real career-defining, country-defining election that we face," he said, immediately correcting himself.