After losing his first race for Nebraska's 1st Congressional District in 1962 to incumbent Ralph Beermann, Callan was narrowly elected to the Eighty-ninth United States Congress in 1964, serving from January 3, 1965, to January 3, 1967.
Following a loss to incumbent Ralph Beermann for Nebraska's 1st Congressional District in 1962, Callan was elected to the Eighty-ninth United States Congress in 1964 and served from January 3, 1965, to January 3, 1967.