Conservative party, in Canada. 1 Former Canadian political party that merged with the Progressive party to form the Progressive Conservative party. 2 Officially the Conservative party of Canada, political party formed in 2003 by the merger of the Progressive Conservative party (PC) and the Canadian Alliance (CA). In 1993 the Progressive Conservatives, who had held a parliamentary majority, were savaged at the polls as many voters in W Canada deserted the PC for the young Reform party (the predecessor of the CA). The PC failed to recover from the losses, and in 2003 agreed to unite with the larger CA against the Liberal party, which had secured three successive victories (1993, 1997, 2000) facing a divided conservative opposition. However, a number of prominent PC members, including former party leader Joe Clark, did not support the union. Former CA leader Stephen Harper was elected Conservative party leader. In the 2004 elections the party's social conservatism failed to resonate with enough voters to force the Liberals from power, despite voter unhappiness with the latter. By the 2006 polls, however, the Liberals had been further hurt by scandal, and the Conservatives secured a plurality of the seats in parliament.