Liberal Leader Stephane Dion has fired off the first official jabs at his counterparts in the federal election, including a message to voters that Stephen Harper is not to be trusted.

Dion said that by announcing the election campaign Sunday, Harper broke his word to Canadians that they would not head to the polls until 2009.

"His last gesture (as prime minister) was a broken promise, and we don't want anymore," Dion told supporters in Ottawa. "We cannot trust this man; it's as simple as that."

Dion also sounded off on the leader of the NDP, Jack Layton. He chastised Layton for echoing the message of "change" made popular by U.S. presidential nominee Sen. Barack Obama in Layton's opening campaign speech.

"Jack Layton for some strange reason thinks he is Barack Obama," Dion told a crowd of cheering Liberal supporters. "No Jack, you're Jack Layton."

For all the tough-talk Dion fired off at the other leaders, he is among the least experienced of the bunch -- Harper, Layton and Bloc Quebecois Leader Gilles Duceppe have all led federal campaigns.

Almost since Dion won the Liberals leadership in December 2006, the Conservatives have attempted to brand the former university professor and cabinet minister as weak and indecisive. The current stock Tory phrase is "not worth the risk."

Dion, who finished fourth on the first ballot of the Liberal leadership convention, tried to paint his reputation as a strength.

"I love it," he said. "I love being the underdog. I love being underestimated, but don't say so, because then I will stop being underestimated."

Canadians will get a chance to know him over the 37 days of the campaign, Dion said, adding, "(Harper) created an expectation so low that I will surprise Canadians."

Carbon tax

Besides attacking Dion's leadership, the Tories have also blasted the so-called Green Shift, which they have tried to paint as a "tax on everything."

Dion said the plan, which he said would shift taxes from income onto pollution, "is a great plan for Canada."

Other governments around the world have introduced carbon taxes, and those that have done so haven't switched back, he said. Even British Conservative Leader David Cameron supports the idea so long as the revenue is balanced by cuts in other taxes, he said.

"Go see TheGreenShift.ca and see what it represents for your family," Dion said, portraying the plan as part of the 21st century economy and crucial to fighting dangerous climate change.

"What Mr. Harper is not saying is we do not add to your tax burden. We shift it towards pollution," he said.

However, Dion announced Green Shift plan changes this past week to ease its effects on those in the farming, forestry and fisheries sectors -- something the Conservatives have painted as a "Green Shift Shift."

The ballot question would be one of leadership, but Dion asked, "leadership for what?

"Leadership to avoid challenges, and to put us on a risky road of the challenges of the competitiveness of the economy, of climate change, of the fact that you have poverty in this country -- and the current leadership is doing nothing," he said. "Or leadership to tackle these issues with Canadians and to win together."