In the 1958 election, Coldwell lost his House of Commons seat, and the party was reduced to a rump of eight MPs. Prime Minister Diefenbaker offered him a Senate appointment, which he declined. In the period following the election, he was constantly considering resigning as the CCF's leader, but was repeatedly dissuaded by the party's executive. However, the party needed a leader in the House of Commons to replace him because he obviously was no longer a member of parliament. The CCF parliamentary caucus chose Hazen Argue as its new leader in the House. During the leadup to the 1960 CCF convention, Argue was pressing Coldwell to step down. The leadership challenge jeopardized plans for an orderly transition to the new party that was being planned by the CCF and the Canadian Labour Congress. CCF national president David Lewis, who succeeded Coldwell as president in 1958, when the national chairman and national president positions were merged,and the rest of the new party's organizers both opposed Argue's manoeuvres and wanted Saskatchewan premier Tommy Douglas to be the new party's first leader. To prevent their plans from derailing, Lewis unsuccessfully tried to persuade Argue not to force a vote at the convention on the question of the party's leadership. There was a split between the parliamentary caucus and the party executive on the convention floor. Coldwell stepped down as leader, and Argue replaced him, becoming the party's final national leader.