Nevertheless, the political leanings of the two cities have persisted over the years to the present. While Calgary has elected mayors in the past who have been known to be Liberals, Calgary was long reckoned as the most conservative major city in Canada. Since 1912, only five Liberals have ever won election to the House of Commons from Calgary-based ridings, none for more than one term. Although the Labour Party of Canada and Social Credit made inroads in the 1920s and 1930s, it was the Progressive Conservatives who dominated federal elections in Calgary, with few exceptions, until the Reform Party swept the federal Tories out of Alberta in 1993. Reform and its successor, the Canadian Alliance continued to dominate in Calgary (and Alberta) until merging with the PCs to form the Conservative Party of Canada. The former Prime Minister, Stephen Harper, represented Calgary Southwest, the riding that had once been held by founding Reform leader Preston Manning.