 Complete the following phrase:  After losing a second successive election in October 1974, Heath insisted he would continue as leader, but in January 1975, Margaret Thatcher announced she would challenge Heath for the leadership, and on 4 February, she narrowly outpolled him in the first round. Heath chose to resign the leadership rather than contest the second round. Heath returned to the backbench, where he would remain until 2001. In 1975, he played a major role in the 