After triggering speculation this past week that the Liberals may be ready for a fall election, party leader Stephane Dion remains coy about when or if his party would try to topple the Conservative government.

"An election will come between now and October 2009," he said on CTV's Question Period on Sunday.

"(Calling an election) is a decision that belongs to me, that's true ... I will choose a good moment."

Last week, Dion fueled talk of a possible fall vote, saying Canadians appear more ready this year to head to the polls than they did last fall.

On Sunday, Dion cited provincial elections in Ontario, Quebec and Saskatchewan as reasons why he chose not to pull the plug last year on Prime Minister Stephen Harper's minority Conservative government.

However, defeating the Tories would require all three opposition parties to agree on election timing and vote down the government.

Dion also defended his Green Shift carbon tax plan, which he said will resonate with voters who will head to the polls in three byelections slated for the fall.

"I will not decide for voters what will be the choices on which issues they want to vote," Dion said. "We have very good reasons to convince these three byelections' voters to vote for the Liberal priorities."

The Liberal "Green Shift" plan includes a $15.4-billion-per-year tax shift that would put a price on carbon emissions and reward green businesses and consumers. The Liberals have said their plan is "revenue neutral" and offsets new taxes with tax cuts, including measures to help lower-income earners.

Dion said Canadians want to make climate change a priority, but acknowledged his plan has its critics.

"We have climate change plans. These climate change plans must be improved ... but the core, to have something that will work, is to put a price on greenhouse gas emissions. Most experts are telling us to do that. Other countries have done it. It did not destroy their economies," he said.

The Tories say Dion's plan will hurt Canadians and businesses and will do nothing to help the environment because it does not call for specific reductions in emissions.

"Mr. Dion is going across the country saying that he wants to raise taxes on just about everything to pay for new spending," Jason Kenney, the secretary of state for multiculturalism and Canadian identity, told Question Period.

Kenney said if the Liberals force an election this fall, voters will consider a host of issues in addition to climate change. He said the Tories will focus on measures to deal with crime and consumer issues when Parliament resumes.

The NDP's Peggy Nash told Question Period her party is ready for an election now.

"Stephen Harper can't be trusted," she said, claiming that's what Canadians have told her about the Tory leader.

"We are really ready to put Stephen Harper's agenda to the public and let Canadians decide because he is taking this country in the wrong direction."