The next year, she entered federal politics and was elected in the by-election held to fill the vacancy created by Bob Rae's departure from federal politics to take the leadership of the Ontario NDP. She defeated senior party aide Gerald Caplan on the third ballot to win the NDP nomination. In the by-election she defeated former "Toronto Sun" editor Peter Worthington, who was running as an independent, by almost 2,000 votes. In the 1984 federal election, she increased her margin to over 3,500 votes again defeating Worthington who, this time, was running as the official Progressive Conservative candidate.