From CBC's Evan Dyer:

The New Democrats are considering whether to pull out of the Munk leaders' debate on foreign policy scheduled for Sept. 28 in Toronto.

Leader Tom Mulcair and his advisers have until tomorrow at noon to decide whether they will participate in the debate, which will focus exclusively on foreign affairs.

Mulcair's campaign team say they were surprised to see the format proposed by the debate's organizers, which would allow each leader to speak as much English or French as they wish.

Debate organizers say those rules conform to the rule around language in Parliamentary debate.

"This isn't Parliament," says one close adviser, who added that the party had agreed to a debate with equal amounts of French and English. The adviser added that New Democrats were concerned that moderator Rudyard Griffiths may not himself be fluent enough in French to ensure a free-flowing conversation in that language.

While Tom Mulcair and Justin Trudeau are both fluently bilingual Quebecers, Stephen Harper learned French later in life.

In recent years, though, he has devoted considerable effort to improving his command of the country's other official language and his French has shown a marked improvement.