On May 4, 1942 Conservative leader
David Duggan died, and his Edmonton seat became vacant. Roper was nominated as the CCF's candidate in the ensuing by-election. The by-election was conducted using
Alternative Voting and Roper, who was not the most-popular in the first round of counting, came out on top after vote transfers. CCF leader
Chester Ronning, who had been elected in 1932, quickly stepped aside to hand the leadership to the party's sole MLA. Roper was leader of the CCF for thirteen years, but he did not have to sit as its lone MLA that long: after the
1944 election, he was joined in the legislature by
Aylmer Liesemer of
Calgary. Two seats were the largest caucus the CCF had during Roper's tenure as its leader. Both Liesemer and Roper were re-elected in the
1948 election. The party's share of the vote fell from 25% to 19%, but it was still due more than 10 MLAs. Roper did not add any new MLAs to his tiny caucus as Social Credit's stranglehold over the province remained intact. The CCF did elect a new MLA in the
1952 election -
Willingdon's
Nick Dushenski - but this gain was cancelled by Liesemer's defeat in the same election. Worse, the CCF's vote fell further, to 14%, and the
Alberta Liberal Party doubled its seat count to four, making it the Official Opposition and leaving the CCF as the third party. Things then got worse for the CCF. In the
1955 election, the CCF's share of the vote was only 8% and the previously dormant Conservatives passed it in the seat count. Moreover, Roper himself lost his seat in Edmonton (although two other CCF MLAs were elected - Dushenki in
Whitford) and
Stanley Ruzycki in
Vegreville). Roper placed third of thirty candidates on the first ballot in the election held using
Single transferable voting, but as Premier
Ernest Manning's large number of surplus votes was redistributed to the city's other Social Credit candidates (and
James Harper Prowse's only slightly smaller surplus was redistributed mostly to other Liberal candidates, Roper fell out of the top seven, where he needed to remain in order to be re-elected. Following the election, Roper relinquished the CCF leadership. He never again sought provincial office. In part this was due to the Manning government switching to First Past the post from the combined STV/Alternative Voting system it had been using. Roper later said he thought that Manning had abolished the STV system in Edmonton to keep Roper from ever getting a seat again. Certainly it worked to the degree that no CCF or NDP again took an Edmonton seat until 1982 - and the change to First Past The Post was likely the main cause of that pattern. ==Municipal politics==