Brian Topp says if he were prime minister he would try to restore the monopoly power of the Canadian Wheat Board. (CP)

Brian Topp, who is seeking to lead the federal New Democratic Party, says if he became prime minister he would reverse the decision to end the monopoly of the Canadian Wheat Board.

Topp noted, however, that it could be a difficult task due to provisions of the North American Free Trade Agreement.

"There's a concern there for sure," Topp said in making the pledge Friday. "It is worth testing it and it highlights that one of the conversations that we likely need to have with our American friends is whether that's really a reasonable provision to have in our trade agreements."

Topp went on to say the free trade deal was in need of updating.

"That trade agreement was negotiated long ago," he said.

"And this is a key point on which it needs a renovation."

Legislation to end the monopoly power of the Canadian Wheat Board is set to take effect Aug. 1.

A challenge over how the federal government introduced the change is still before the courts.