What exactly are MP's voting on today?
There are two bills before House today.
The first is bill C-43, which would essentially approve the spending laid out in the Liberal's 2005 federal budget.
The second vote is an amendment to the federal budget, bill C-48, that would allow an additional $4.6-billion in spending, which was originally allocated in the budget for corporate tax cuts.
Under the amendment, the funds would be redirected to affordable housing, post-secondary education, foreign aid, and the environment.
The amendment came as a result of an agreement between the Liberals and the NDP, in exchange for NDP support on the budget.
The Tories and the Bloc Québécois support the original budget, but not the additional spending in the amendment.
Why is the budget considered a confidence vote?
Parliamentary tradition holds that a budget is a confidence motion for the government.
The belief being that if the House doesn't approve of the government's spending priorities as laid out in the budget, it also does not have confidence in the government itself.
Both the Throne Speech and the budget could potentially topple the government if they fail a vote in the House.
The last time an election was called over a budget was in 1979, when the Joe Clark's Tory government lost the confidence of the House over its first budget.
At any time, the government can make a bill a confidence motion, meaning that if the bill fails, the government will fall. Government's have been known to engineer their own defeat in minority governments, when they think they could win an election.
The opposition can also introduce a no-confidence motion, if it believes the government has lost control of the House.
Prime Minister Paul Martin said last week that Thursday's budget vote would be considered a confidence motion and if it fails, he will call an election.
What's the lay of the land going into the vote?
The Liberals have 152 votes, including the 19 NDP votes and independent MP Carolyn Parrish, who says she will support the government.
The Conservatives and the Bloc Québécois have 152 votes combined.
There are two independent MPs that have yet to decide, Chuck Cadman and David Kilgour. In an eleventh hour decision Thursday, Mr. Kilgour said he would side with the Conservative opposition.
The Liberals would need the vote of at least one independent, in which case, the speaker, Liberal MP Peter Milliken, would break the tie and cast his deciding vote in favour of the government.
If both the undecided MPs vote with the Tories and the Bloc, the government will fall.