In another sign the NDP is a true contender to form government, protesters are starting to show up at campaign events.

Monday morning, a small group of activists opposed to the Energy East pipeline disrupted NDP Leader Tom Mulcair's book launch in downtown Toronto and were swiftly removed by security.

A similar disruption happened a week earlier, when two Energy East opponents managed to get inside Mulcair's post-debate rally at a Toronto hotel. (Although the protesters admitted afterwards they support the NDP, but felt compelled to promote their activism to send a message).

NDP Protesters

Mulcair has been forced to walk a very fine line over the NDP's vague support of the project.

Energy East would send crude oil from the Prairie provinces to refineries in Eastern Canada.

The project is strongly opposed in Mulcair's home province of Quebec, but it enjoys widespread support in the Prairies - an area the NDP needs to gain.

Mulcair says he supports the concept of Energy East, but it requires strong environmental assessments.

The NDP's critics, including Liberal Leader Justin Trudeau, and Bloc Leader Gilles Duceppe, accuse Mulcair of double speak: sounding pessimistic against the project in French, while striking an optimistic tone in English.