St. George had been a staunchly Tory seat for decades, and Campbell faced a prominent opponent in Roy McMurtry, but she was victorious becoming the first woman elected as an Ontario Liberal Party MPP.[3] She was re-elected in 1975 and 1977.[4][5] She represented the riding until 1981, advocating on issues related to poverty, and in favour of women's and gay rights.[4] She resigned her seat prior to the 1981 election so that she could spend more time with her ailing husband.