Prime Minister Stephen Harper says it is "disappointing" that the NDP's interim leader was once a member of the Bloc Quebecois, but Nycole Turmel said while she regrets her association with the separatist party she will not step down from her post.

Controversy has swirled around Turmel since she confirmed Tuesday that she was a card-carrying member of the Bloc for about four years before turning in her card in January. She is also a member of the provincial Quebec Solidaire, but says she intends to let her membership lapse.

"I think it's very disappointing," Harper said when asked about Turmel by reporters while handing out scholarships at McMaster University in Hamilton, Ont. "I don't know that I have a lot to say but I do think Canadians will find this disappointing. I think Canadians expect that any political party that wants to govern the country be unequivocally committed to this country. I think that's the minimum Canadians expect."

Turmel has hit back hard at her critics since news of her political affiliations broke, saying she joined the Bloc to support her friend, former Bloc MP Carole Lavallee. Lavallee held the seat in Saint-Bruno--Saint-Hubert from 2004 until her defeat in the May election.

In an interview with CTV News Channel Wednesday, Turmel would not respond directly to Harper's remarks. However, she maintained her previous assertions that she is a federalist, pointing out that she voted against Quebec's separation in the last referendum.

Turmel also said that despite the uproar, she won't step aside from her post saying, "I've been elected to the job. I will do it."

"I regret the signing of the card…but that doesn't prevent me (from doing) my job," she said. "I have the confidence of Jack Layton, I have the confidence of my party."

When asked about her affiliation with Quebec Solidaire, Turmel said she became involved with the party because there is no provincial wing of the NDP in Quebec, and she is interested in many of the social causes that the party espouses, such as affordable housing and other anti-poverty measures.

"That's my background, so it's normal that I (would) work with people who have a social background," she said.

NDP officials have also defended Turmel, saying she has been a member of the party for more than 20 years and served as an associate president in the 1990s. Spokesperson Karl Belanger also pointed out that she co-chaired an NDP forum on Canada's future.

After a career in union advocacy, Turmel was elected the New Democrat MP for the Quebec riding of Hull-Aylmer in the spring election as part of an NDP surge in the province that vaulted the party to official Opposition status, essentially wiping out the Bloc. Shortly afterward, she was unanimously elected caucus chair.

"Quebec said it," Turmel said of the election results. "Quebec told us they didn't want the Bloc Quebecois party anymore, they wanted a federalist party. They voted for us and we'll do the job we were elected for."