The Liberals are threatening to bring down the government over the latest federal budget as early as next month, but will likely avoid triggering an election Thursday when MPs vote on a motion designed to kill the Registered Education Savings Plans bill.

Liberal Leader Stephane Dion has had his party abstain on crucial confidence motions in the past, arguing Canadians were not yet ready to head to the polls. But his finance critic signalled a different position Tuesday.

"We have said that we would not bring the government down at this time before Easter, but come April or May or later in the session circumstances might have changed," John McCallum said.

"Later on in the session, all options are open."

An emerging point of contention between the two parties is the RESP legislation, a private member's bill introduced by Liberal MP Dan McTeague.

The bill has already been approved by the House of Commons and is now before the Senate. It would allow parents to contribute up to $5,000 annually for each child and deduct the amount from their income taxes.

Conservatives say the bill is far too costly and could result in a deficit if given royal assent.

Finance Minister Jim Flaherty has introduced a ways and means motion attached to the federal budget that would effectively kill the RESP bill.

The motion is a preliminary procedural requirement for bills that involve taxation, and the House of Commons will put it to a vote on Thursday.

Liberal MP Marlene Jennings said the motion was effectively a "poison pill" designed to force an election, but that her party would side-step the measure.

"Mr. Dion has said repeatedly that we are not prepared at this point in time to bring down the government," she told CTV's Mike Duffy Live. "Therefore, on that ways and means motion, we will not bring down the government. We won't do it."

She also said Flaherty had plenty of time to prepare for the RESP bill without letting it become the subject of a confidence motion.

"(McTeague) tabled his plan almost two years ago, in May 2006, shortly after this government brought in their first budget," Jennings said.

"The minister of finance has had almost two years to develop a contingency plan to deal with that bill on the chance that it might get approved by the House of Commons and then ultimately by the Senate.

"He sat on his hands, he made choices to empty out the public coffers for their ideological wish list, brought us to the brink of a deficit with their own budget, and then tries to turn around and say it's the Liberals that are going to bring us to a deficit."

McCallum said the Liberals would vote against the motion Thursday, but only in limited numbers so the government would not fall.

However, he added that his party may still bring down the government over the budget implementation legislation that will proceed from the motion.

That motion will likely take until next month to reach the House of Commons, but will also include a provision to kill the RESP bill.

"We'll examine it and we may or may not support it," he said. "We may propose an amendment."

McCallum added that the Liberals could also vote against the budget because the government has failed to plan for a sufficient budgetary surplus to cushion the blow if Canada's economy hits a downturn.

With files from The Canadian Press