Meighen, lacking a Commons seat, resigned from the Senate on 16 January 1942, and campaigned in a by-election for the Toronto riding of York South. His candidacy received the improbable support of the Liberal Premier of Ontario Mitchell Hepburn; this act effectively hastened the end of Hepburn's Liberal Premiership, and did not in any case grant Meighen durable electoral support. The Liberals did not run a candidate in the riding due to a prevailing convention of allowing the Opposition leader a seat. Still harbouring a deep hatred for the Conservative leader and thinking that the return to the Commons of the ardently conscriptionist Meighen would further inflame the smouldering conscription issue, King arranged for campaign resources to be sent to the Co-operative Commonwealth Federation's Joseph Noseworthy. Federal Liberal support and rising CCF fortunes ensured that Meighen was defeated in the 9 February 1942 vote.
With its leader excluded from the Commons, the Conservative Party was further weakened. Meighen continued to campaign for immediate conscription as part of a "total war" effort through the spring and summer, but did not again seek a seat in the House of Commons. In September, Meighen called for a national party convention to "broaden out" the party's appeal. It remained unclear whether Meighen sought to have his leadership confirmed or to have his successor chosen. As the convention neared, news sources reported that Meighen had approached Manitoba's Liberal-Progressive Premier John Bracken about seeking the leadership, and that the convention would adopt a platform that would move the party toward acceptance of the welfare state. Meighen announced in his keynote address to the party on 9 December 1942 that he was not a candidate for the leadership and the party subsequently chose Bracken as leader, and renamed itself the Progressive Conservative Party of Canada.