He said things along these lines  more than once during the campaign but it is clearly laid out in "Full text of Rosemary Barton's interview with Stephen Harper", October 6, 2015. (There is no mention of the debt-to-GDP ratio in the interview.) Rosemary "Anyone But Harper" Barton takes the Liberal promise to run deficits only for three years as an article of faith. Harper replies, accurately as it now appears, that running multiple deficits when the economy is growing is a formula for perpetual deficits.