The date for the next federal budget is set for Tuesday, March 22, which means there is less than three weeks to go until Canadians could learn whether they will be heading to the polls for a spring election.

The opposition parties will not necessarily pronounce that day whether they will support Prime Minister Stephen Harper's sixth budget or not, but based on the lines they've already drawn in the sand, it may not be hard to guess.

The Liberals, NDP and Bloc Quebecois have all made it clear what they want to see in the budget and Finance Minister Jim Flaherty has also given some indications of whether they will find what they're looking for.

"There will be nothing about corporate taxes in the budget. Nothing," Flaherty said emphatically on Wednesday when he announced the budget date.

Liberal Leader Michael Ignatieff has been demanding a rollback of the corporate income tax rate to 18 per cent, from the 16.5 per cent rate to which it was cut in January. If he sticks to his position that the government is making poor spending choices that his party won't support, the budget vote's fate will be left up to one of the other two parties.

The NDP's stated wishlist includes help for seniors and lifting the GST on home heating bills, while the Bloc Québécois wants more than $2-billion in compensation for Quebec for harmonizing the provincial and federal sales taxes more than a decade ago. Ottawa and Quebec are in the midst of negotiations on that issue and Flaherty said Wednesday that he hopes an agreement is reached soon, but whether that will happen before March 22 is not clear.

The finance minister hinted he might include items in the budget that will appeal to the opposition parties and he noted that the document is still a work in progress. "We're still open-minded," he told reporters. "The books are not closed."

In other words, the parties could keep talking on possible budget measures to see if an election could be avoided.

Flaherty said there would be no big spending programs announced in the budget, but he did mention senior citizens specifically as a group of Canadians his government might do more to help. That's a priority area for the NDP.

Flaherty has met with all of the finance critics from the opposition parties, and said some of those discussions would continue leading up to March 22. He didn't specify whom he would be talking to in the coming days but said "some parties" are not interested in what the budget will contain and instead want to force an "unnecessary and opportunistic election."

None of the opposition leaders has vowed in advance to vote against the budget, including Ignatieff; all have said they will review its contents first before taking a position.

"There are some discussions that are continuing. I expect there will be some items in the budget that will engender consideration by opposition parties," said Flaherty. "At least I hope so."

In addition to further talks with the opposition parties, Flaherty also intends to meet again with private sector economists before he puts the finishing touches on the budget. Those meetings will take place next week, the finance minister said.

He wants the most up-to-date economic forecasts possible from the fiscal experts so that he has the latest data on Canada's economic growth and other indicators.

"We haven't finalized the budget. We have more work to do," he said.

The budget itself is only printed a few days in advance of its presentation, he reminded reporters.