• Claude Wagner, 50, was the front-runner going into the convention. A former Liberal Minister of Justice in the government of Quebec. Wagner's support came from party members who believed that having a Quebec francophone leader would enable the party to expand its support in Quebec, where the party was usually soundly defeated by the Liberal Party of Canada in elections. Wagner's law-and-order image as Quebec justice minister appealed to many on the party's right wing.
• Brian Mulroney, 36, was a lawyer from Quebec who had grown up in a bilingual family and was also seen as a candidate who could appeal to Quebec. Mulroney had never run for public office before, however, and alienated many party members with his slick appearance and his very expensive campaign. Key operatives in Mulroney's campaign included Ontario PC president Alan Eagleson and Newfoundland Premier Frank Moores. Mulroney was endorsed by only two sitting Members of Parliament, Heath MacQuarrie (Hillsborough) and James McGrath (St. John's East).^[2]
• Joe Clark, 36, had been the Member of Parliament for Rocky Mountain, Alberta since the 1972 federal election. A Red Tory, in his youth he had served two terms as president of the Progressive Conservative Youth wing. Prior to being elected to parliament, Clark was a journalist, political science teacher, and party worker.^[1]
• Jack Horner, 48, had been a Member of Parliament from Alberta since 1958 and was a cattle rancher. He was considered to be a maverick and attracted votes from right-wing westerners. Horner was endorsed by former Prime Minister John Diefenbaker.^[1]
• Paul Hellyer, 52, was a popular, long-term Liberal cabinet minister from Toronto who had been defeated by Pierre Trudeau at the 1968 Liberal leadership convention. After leaving the Liberal Party, Hellyer had attempted to establish a new party under his own leadership, the Action Canada movement. This was unsuccessful, and Hellyer joined the PC Party. Hellyer seriously damaged his bid for the PC leadership during his convention speech, when he criticized centrist Red Tories in the party for not being conservative enough. This alienated many party members who saw the irony in a former Liberal cabinet minister lecturing party members about being conservative.
• Flora MacDonald, 49, a popular PC Member of Parliament from Kingston, Ontario, was the first woman to make a serious run for the PC leadership. (Mary Walker-Sawka had won two votes at the 1967 leadership convention.) MacDonald encouraged women of all political stripes across Canada to support her campaign by contributing one dollar. She was believed to be the front-runner amongst the Red Tory candidates going into the convention. Based on the public statements of support that she had received from delegates, many believed that she had a realistic chance of becoming leader. She had been endorsed by New Brunswick Premier Richard Hatfield.^[2]
• Sinclair Stevens, 49, an Ontario businessperson and PC MP for York—Simcoe since 1972.
• Pat Nowlan, 44, the Member of Parliament for Annapolis Valley, Nova Scotia, had sat in parliament since 1965.^[2]
• Heward Grafftey, 47, was the MP for Brome—Missisquoi, Quebec.
• James McPhail Gillies, 51, was the MP for Don Valley in Toronto, Ontario.
• John Fraser, 44, was the MP for Vancouver South, British Columbia.

Richard Quittenton, president of St. Clair College in Windsor, had also been a candidate but withdrew before the first ballot and endorsed Wagner.

The first ballot was widely expected to be a close contest between Wagner and MacDonald, though it was thought unlikely that either of them would have a decisive lead. The result proved a shock to everyone at the convention, as while Wagner did about as well as had been expected, MacDonald did far worse than even the most pessimistic predictions had indicated, coming in sixth place; the phenomenon of delegates promising their votes to one candidate and then voting for another has become known in Canadian politics as the "Flora Syndrome". Mulroney was slightly ahead of the rest of the chasing pack, but still over seven percentage points behind Wagner, who was now the clear front-runner. Grafftey was automatically eliminated after finishing in last place, with Gillies and Stevens dropping out of their own accord; all three endorsed Clark.

While Wagner extended his delegate count on the second ballot, Clark saw the most dramatic improvement in his delegate count, nearly doubling it from the first round. Mulroney dropped down to third place and made only minimal gains. MacDonald, having remained on the second ballot in the hope that she might pick up some Red Tory delegates from the candidates who dropped out, likewise earned only a small number of extra delegates; realizing that the situation was hopeless and that she would most likely be eliminated next if she remained on the ballot, she withdrew and threw her support behind Clark, as did Fraser, who was automatically eliminated in this round. Nowlan withdrew and initially intended to endorse Horner, but the latter, sensing that the momentum was with Clark, persuaded Nowlan that they should both endorse Wagner to prevent a split in the right-wing vote. Hellyer followed their lead and also endorsed Wagner.

The third round had Wagner continuing to lead, but only barely, with both he and Clark having picked up large numbers of delegates since the previous round, albeit Clark having done slightly better in that regard. Conversely, any momentum that Mulroney had completely stalled, causing him to actually lose delegates and be automatically eliminated. While it was now clear that Mulroney was in a position to be the kingmaker, he simply left the convention after his elimination was announced and did not endorse either Wagner or Clark; this created an unpredictable scenario, as about half of Mulroney's delegates were favourable to Wagner because he was a fellow Quebecer, while the remaining half were favourable to Clark due to his political positions being closer to Mulroney's.

Ultimately, Mulroney's delegates were sufficiently favourable to Clark to afford him a narrow victory on the final ballot. Clark's majority over Wagner was just 2.8%, making this the most closely contested election for the leadership of a major Canadian political party until that point, surpassed in the years since only by Andrew Scheer's victory over Maxime Bernier (with a majority of 1.9%) in the 2017 Conservative Party of Canada leadership election.

• Progressive Conservative leadership elections