Mr Romney, 62, was sitting in the economy section of an Air Canada flight from Vancouver to Los Angeles on Monday when he asked a man sitting in front of his wife, Ann, to raise his seat back.
A spokesman for the former Massachusetts governor said the passenger became enraged and tried to hit him.
Mr Romney did not retaliate and his assailant was removed from the flight by police after the pilot returned to the gate, said the spokesman.
Uncharacteristically impolite Canuck? Or characteristically psycho American moonbat? Inquiring minds want to know.