NDP Leader Tom Mulcair has been dogged by protesters the past two days while touring four southern Quebec ridings his party hopes to win in the upcoming federal election.

There are some questions he just can't shake.

This afternoon he spoke on the plaza in front of Quebec City's Chateau Frontenac in front of about 300 people, and while the crowd was supportive, he was confronted again by a small group of protesters calling him out for backing the Energy East pipeline, which is controversial in Quebec.

Mulcair has been accused of being less supportive of it in French than in English and offered his most nuanced explanation so far.

"It's as big a mistake to be against something that's never been studied thoroughly as it is to be in favour of something that's never been studied thoroughly," he said.

Rigorous study

Mulcair has said he would only allow the pipeline if it passed rigorous environmental study.

The NDP leader was less clear on the economy. Asked how he'd fulfil promises to cut business taxes and offer programs like universal daycare, he said the party will come out with a costed platform later in the campaign.

For the first time he took a shot directly at Liberal Leader Justin Trudeau, who earlier in the day spoke of growing the economy "from the heart outwards."

Mulcair called that rhetoric, saying "instead of growing from the heart, have a heart help us bring in programs like $15 a day daycare."

Mulcair's next public stop is Friday in Toronto. He heads West next week