NDP leader Tom Mulcair says it is important for the next leader of his party to have a seat in the Commons – an issue playing out in the current battle to replace him.

Mulcair says questions quickly came up about his lack of a federal seat when he became the Quebec lieutenant to late NDP leader Jack Layton, prompting him to run in a federal by-election in 2007.

Ontario legislator Jagmeet Singh is the only contender in the NDP leadership race without a seat in the Commons.

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He is running against three sitting MPs: Manitoba's Niki Ashton, Quebec's Guy Caron and Ontario's Charlie Angus.

Mulcair says he thinks it would be "a heck of a lot better" for the next leader to cross swords on a daily basis with Prime Minister Justin Trudeau.

The party is set to announce his replacement in October.