Liberal Leader Stephane Dion said he takes full responsibility for a key byelection loss to the NDP in Quebec on Monday, and vowed the party will perform better next time.

"It's my responsibility to win the byelection and I take the responsibility for what happened and the responsibility to be sure that next time we'll be stronger," Dion said during a news conference on Tuesday.

"We may have a national election -- a general election, or a byelection in Saskatchewan, Ontario, and British Columbia. We intend to win these byelections or a general election."

The Liberals came up empty-handed in three byelections held Monday, while the Tories and NDP gained ground.

The Conservatives managed to take a seat in the Bloc Quebecois stronghold of Roberval--Lac-Saint-Jean, while NDP challenger Thomas Mulcair took the longtime Liberal stronghold of Outremont from Jocelyn Coulon.

The Bloc held onto the remaining Saint-Hyacinthe-Bagot east of Montreal, fending off a strong challenge from the Tories.

Dion denied that the losses in Quebec have led to a leadership crisis. He said the Liberal Party now knows it must work harder if it is to build support in the next election.

"We will ask a lot of questions about how can we improve the situation to make sure we win the next election," Dion said.

"We have a burden of responsibilities on our shoulders. We really think that this government is bringing Canada in the wrong direction and we need to win for the good sake of Canada."

Dion, a Quebecer, was elected as leader partly on his promise to gain ground for the Liberal Party in Quebec.

He said Monday's loss was a reflection of the fact the Liberal Party faces challenges in Quebec, and he intends to have an "intense dialogue" with people in the province in the coming weeks and months to get the Liberal message across.

Mulcair, a former Liberal environment minister in Quebec, told CTV Montreal he sees his victory as a major milestone for the NDP, which has only ever held one seat in the province.

"I think what you're going to see as we head into the next general election, there are a lot more people like me who are household names in Quebec who realize the NDP is the way of the future, for our kids, for Canada getting back to its pre-eminent role on the world stage that we've lost with the Harper Conservatives."

Speaking on Tuesday, Mulcair said the victory came down to hard work by his campaign team, the NDP's position on the war in Afghanistan and the party's strong environmental stance.

NDP Leader Jack Layton said Mulcair's win in Outremont, a riding held by the Liberals since 1935 with only one exception, represents a "very significant change, a new era in politics in Quebec and therefore perhaps in Canada."

"It's the beginning of a process," Layton told CTV's Canada AM on Tuesday morning.

"With a voice of such integrity and capacity as Thomas Mulcair, speaking out against the Harper policies on the war, speaking out so strongly on the environment where he's so well known, and for the priorities of working and middle-class families which are really feeling squeezed out there."

One analyst said Mulcair's victory in what has historically been considered a safe Liberal riding, to a candidate hand-picked by Dion, will undoubtedly trigger questions about his leadership skills.

"I think the question that's being asked is: Why or how can Stephane Dion now claim, as he did during the Liberal leadership race, that he would bring Quebec back to the Liberal Party? How has that promise not been fulfilled and how do they keep the Liberal brand from sliding further?" Antonia Maioni, director of the McGill Institute for the Study of Canada told CTV's Canada AM on Tuesday.

She said two key battlegrounds are emerging in Quebec -- one on the island of Montreal, where the Liberals have historically dominated, the other throughout the rest of Quebec, where the Liberals seem to be losing ground among francophone Quebecers while the Tories seem to be gaining traction.

The Conservative victory in Roberval--Lac-Saint-Jean seemed to indicate that Harper's 18-month courtship of the province had paid off.

"I think in the short term, the NDP victory is a very good one for the party. But I think in the long-term, it's the Conservatives who have shown that they are emerging as a federalist alternative in the rest of Quebec that is off the island of Montreal," Maioni said.

One anonymous Liberal MP pointed out to the Canadian Press that the Liberals' current seat count in Quebec -- 12 of 75 -- is the lowest since Confederation.

"There are going to have to be changes in the leader's entourage," said the MP.

The Conservatives now hold 126 seats in Parliament, while the Liberals have 96, the Bloc 49 and the NDP 30.

Three seats are held by Independent MPs and four remain vacant.