Liberal Leader Justin Trudeau says Conservative Leader Stephen Harper should fire some of his senior staffers.

It's over revelations this week about the $90,000 payment from Harper's former chief of staff, Nigel Wright, to cover Senator Mike Duffy's questioned expenses.

When it was revealed in June 2013 that Wright gave Duffy the money out of his own pocket, Harper insisted Wright was the only PMO staffer in on the scheme.

But Duffy's trial has heard evidence this week that half a dozen PMO staff and Conservative Party brass were in the know about Wright's plan — including Ray Novak, Harper's current chief of staff.

Harper changed his tune Friday, telling reporters in the Northwest Territories that the "vast majority" of his staff didn't know about the plan.

Before the payment became public, the plan was to say Duffy repaid the expenses.

On Saturday, Liberal Leader Justin Trudeau called on the prime minister to fire the staffers who knew about the plan to repay Senator Mike Duffy's questioned expenses. (Liam Richards/Canadian Press) Trudeau said Saturday in Toronto that Harper's closest advisers "conspired to mislead the Canadian people and instructed ministers of the Crown to mislead Parliament."

"Stephen Harper picked these people, he hired them, he promoted them, he protected them and he's keeping them on the public payroll while they run his election campaign even though he knows full well everything that they did," Trudeau said while attending a union event at a Toronto park.

"If Stephen Harper had any respect left for the office he is privileged to hold, he would fire these people immediately."