MONTREAL - Gilles Duceppe launched the sixth election campaign of his political career Saturday by aggressively attacking Stephen Harper.

The Bloc Quebecois leader responded as the Conservative leader kicked off his campaign for the May 2nd election by warning the Liberals against a slapdash coalition that would include the separatist Bloc party and the NDP.

"It's unacceptable to have the Bloc make decisions," said Harper. "Imagine a coalition of arch-centralists and Quebec sovereignists trying to work together."

Duceppe brandished a letter Harper wrote in 2004 to then-gov. gen. Adrienne Clarkson, urging her to consider a Harper-led coalition with the NDP and the Bloc against then-prime minister Paul Martin.

Duceppe said Harper is not being honest when he says he never sought a coalition against the Liberal government.

"He wrote it. We're not rewriting history -- he is," said Duceppe. "He lied this morning. He lied."

The Conservatives have defended their stance, saying the 2004 agreement was never described as a coalition, but as a "co-operative effort."

"In 2004 I made it very clear that I would not form a coalition. Same thing in 2006, same thing in 2008 and same thing now. If we don't win, we don't form a coalition that's democracy," Harper said on Saturday.

But Duceppe said Harper was lying about his 2004 plans, and that Harper met with him to discuss details and a legislative agenda.

"He came to my office and said, ‘What do you want in the speech from the throne?'" Duceppe said.

Duceppe has not committed to a coalition, stating the needs of Quebec would need to be addressed if a union was formed.

"They all come to us. They all want to be in our bed, but don't want to marry us. It's their problem, not ours."

With files from La Presse Canadienne, The Canadian Press and CTV.ca News Staff