RIVIERE-DU-LOUP, Que. — Stephen Harper is rejecting the notion of working with the other parties to come up with a compromise that would save a Conservative government from defeat if his party wins another minority.

"I don't accept the question," Harper said Wednesday when asked if he'd be willing to work with the other parties in a minority setting.

Meanwhile, Liberal leader Michael Ignatieff blasted his Tory rival for suggesting there was no need to compromise on the budget tabled last month, in another minority situation.

And Bloc Quebecois leader Gilles Duceppe said his party would not join a coalition of political parties in a minority Parliament, no matter how the vote shakes out on May 2. He added that he and his MPs would be willing to co-operate with other parties on a case-by-case basis, depending on what the Bloc believes to be in the best interests of Quebecers.

Earlier this week, Ignatieff said in an interview that he'd be willing to work with leaders of the other parties — "even Mr. Harper" — if Canada once again, finds itself with a minority Parliament.

But Harper shot down that possibility Wednesday, saying he believes the Liberals, NDP and Bloc have already decided to team up to defeat the Conservatives soon after the election, to form a coalition government.

"If you look at what they're saying in this campaign, it is very clear. They're saying that even if we receive a mandate from the people, they will defeat us on our budget if they can. They will get together and form another alternative of some other kind of government."

Harper has explicitly asked voters for the first time to give his party a majority, which will require the Conservatives to add at least 12 seats to the 143 the party held at dissolution.

Results of recent polls suggest a majority is far from assured.

The Conservative leader said Wednesday he would be "honoured with any mandate" his party receives from voters on May 2. But he refused to discuss what changes to the party's platform he would be willing to accept to keep the Conservatives in power if they win another minority.

Instead, Harper ratcheted up his rhetoric about the prospect of a coalition, calling it a "black hole" that would stall the economic recovery, provoke more constitutional squabbling and trigger a "national-unity crisis." He was likely referring to comments by Jack Layton in the English-language debate, in which the NDP leader said he was open to another debate on how to get Quebec to sign the Constitution.

Harper also declared that an opposition coalition would lead to another referendum on whether Quebec should separate from Canada, even though it would be up to the provincial government to put forward such a vote.

"We don't know what that government will stand for," Harper said, of a possible coalition. "But we do know the general outlines. There's no focus on the economy. There are tax hikes, and, of course, these parties have very dangerous and conflicting views on national unity and constitutional matters.