Garneau later challenged Trudeau to a one - on - one debate .
Garneau later said that if Trudeau could not defend his ideas in a debate against him , he would n't be able to do so against Prime Minister Harper .
Garneau later challenged Trudeau to a one - on - one debate , and said that if Trudeau could not defend his ideas in a debate against him , he would n't be able to do so against Prime Minister Harper .