Front-runner Peter MacKay has won the leadership of the Progressive Conservative Party.

He won in a fourth ballot with 64 per cent of the votes, beating Calgary lawyer Jim Prentice, the last of three challengers. MacKay led on every ballot, and had been expected to win.

In his acceptance speech, MacKay called for party unity and said the Tories are the only alternative to the governing Liberals. Unity "is job one," he told the CBC's Peter Mansbridge.

MacKay underlined the point by saying he called a caucus meeting for Sunday morning, and invited Prentice.

He won after being backed by Saskatchewan farmer David Orchard, who was eliminated from the final ballot after coming last in the third.

MacKay, a Nova Scotia MP, received 1,510 votes. Prentice received 836.

Scott Brison, also a MP from Nova Scotia, was knocked off the third ballot because he came last in the second.

Fourth-ballot results
Peter MacKay 64%
Jim Prentice 36%

MacKay's victory was controversial because many of the delegates feared that he agreed to reconsider Tory support for free trade as the price of Orchard's support.

But in his speech, MacKay said free trade "has been a big winner for our country," and the Conservatives "will study the ways to improve the deal."

That will involve a review of the deal. But the agreement itself calls for a review, he pointed out.

"The benefits of free trade are clear," he told Mansbridge. "We are the party of free trade."

He also said he would be willing to talk to Canadian Alliance Leader Stephen Harper about uniting the two right-wing parties, but it would be on the Conservative's terms, and the idea is not a priority.