Liberal Leader Stephane Dion and the other opposition party leaders say they don't think the minority Conservative government will last through 2008.

They suggested in interviews with CTV's Question Period on Sunday that the spring federal budget could be defeated by a non-confidence vote, thus triggering an election.

 Dion said Canadians have become frustrated with the Conservative government's policies, specifically their mismanagement of environmental issues.

"After two years of this minority Conservative government, the psychological threshold will have been reached," Dion said. "People may not want, necessarily, an election, but they will not be surprised if there is one."

However, Dion also told co-host Craig Oliver, "If there is an election -- I know you will ask me the question, and I don't know the answer more than you."

Dion spent much of the fall dodging chances to force an election. Liberal MPs abstained from voting on the throne speech. If the opposition had voted the speech down, a federal election would have been triggered.

NDP leader Jack Layton -- whose party did vote against the throne speech, along with the Bloc Quebecois -- blamed Dion for letting Harper stay in government.

"He has been propping up Mr. Harper all fall, and abstaining on a throne speech that's explicitly said we'll stay in Afghanistan longer, we will abandon Kyoto and we'll give huge tax reductions to those doing well," Layton told Question Period.

Dion said he personally found it very difficult to not vote down the government, but after discussing it with his team, he decided Canadians did not want an election in 2007.

Forcing an election on Canadians would have been detrimental to the party, he said.

"I'm a team player, I'm very collegial, I work hard and I listen to the people and I make up my mind. Sometimes I don't follow the view of my advisers, and sometimes I do," Dion said.

A recent Strategic Counsel poll suggests the Liberals and Conservatives are neck and neck, which could signal the time is coming for Dion to force an election. A new budget to be announced some time before March 31 could be the trigger, but Dion wouldn't confirm anything.

"Polls are, for me, an indicator, it's not a master," he said. "We need to see the budget, we need to see the bills that the government is proposing, and then we'll vote accordingly."

Bloc Quebecois Leader Gilles Duceppe said he will set out his party's conditions for the budget, but doesn't hold much hope that the Conservatives will implement his suggestions.

"I don't see how their budget will be supported by any of the opposition parties," he told Question Period.

He said the major campaign issues in Quebec will be Harper's stance on the environment, Afghanistan and the economy - none of which he shares with the province's public opinion.

Layton said when an election is triggered, trust in Harper will be a major issue. He said the Conservatives have taken Canada down the wrong path in terms of environmental issues and the war in Afghanistan.

Green Party leader Elizabeth May said the biggest issue in the next election will be "whether we want a livable world for our children."

She told Question Period that the odds were an election call would come from the budget, unless Dion toppled the government first.

An opposition day -- a day when opposition parties can move any motion, including a vote of no confidence in the government -- could be scheduled first, she said.

In an earlier interview with Â鶹´«Ã½, Harper said the budget will be introduced "fairly early in the spring."

In terms of an election's likelihood, he said: "I don't see anybody chomping at the bit to defeat us for the last two years, so I think we feel pretty good about things."