By Lee Carter BBC News, Toronto

Canada's minority Liberal government received some surprise help in its bid to stave off a Thursday vote of no confidence, when a senior member of the opposition Conservative party announced that she was joining the Liberals.

Martin was happy to welcome Stronach into government

Belinda Stronach, 39, who was regarded as a Conservative front-bench star, made the unanticipated announcement at a news conference with the Canadian Prime Minister Paul Martin.

She cited differences with her party leader Stephen Harper over issues such as the party's opposition to legislation that would legalise same-sex marriage.

She said she was uneasy at the Conservatives forging a voting alliance in the House of Commons with the Quebec separatist party the Bloc Quebecois.

And she mentioned opposition to her party's determination to force an election, just a year after Canadians last went to the polls.

"I find myself at a crossroads forced on me by the leader of the Conservative Party trying to force the defeat of this government this Thursday," she said.

"But I regret the party leader is not truly sensitive to the needs of each part of the country and just how big and complex Canada really is."

The Conservatives and the Bloc Quebecois have been determined to topple the Liberal government, which has become embroiled in a corruption scandal, involving millions of dollars of wasted Canadian taxpayers money in the late 1990s.

She was seen as a younger, more moderate female voice for a renewed Conservative party Kady O'Malley Journalist

The addition of Ms Stronach to Mr Martin's cabinet increases his chances of keeping his minority government alive for Thursday evening's no confidence vote, ostensibly on the Liberal budget.

But it is by no means a foregone conclusion.

Her defection from the Conservatives gives the voting coalition of the Liberals and the left-wing New Democrats a total of 151 votes.

The Conservatives and the Bloc Quebecois have a total of 152 votes.

However there are three Independent MPs. One says she will vote with the Liberals, the other two have not said which way they will vote.

In the event of a draw, the Speaker of the house, a Liberal, would cast the deciding vote.

'Symbol of vitality'

Conservative leader Stephen Harper acknowledged that the loss of one of his front-bench MPs makes the defeat of the government less likely.

But he says that he is glad that this happened now rather than during an election.

Harper admits the government's defeat is now less likely

"But it doesn't in any way change the principal position that our caucus has taken on this issue. The governing party is corrupt," Mr Harper said.

Kady O'Malley is a journalist for the Ottawa parliamentary newspaper The Hill Times. She says regardless of who wins the vote Ms Stronach's defection has wounded the Conservatives.

"She was seen as a younger, more moderate female voice for a renewed Conservative party," Ms O'Malley said.

"She was someone they could always point to when the Liberals or New Democrats tried to accuse the Conservatives of being made up of grumpy old men.

"There are other dynamic women MPs in the party, but it's a real blow, Belinda really was a beacon."

Ms O'Malley says that the loss of Ms Stronach opens up old divisions in the relatively new Conservative party and calls into question Mr Harper's leadership.

"Stronach was seen as a symbol of the party's viability in urban constituencies and in central Canada, which the Conservatives have found hard to crack.

"It harkens back to the traditional clash between the more moderate Tories and the hard-line social conservatives from Alberta and western Canada.

We've seen this flare up before and this is another example of that division."

Corruption scandal

The dramatic development is just the latest in a chaotic series of events to engulf Canadian politics.

Last week the opposition alliance of the Conservatives and the Bloc shut down parliament for three consecutive days, by winning parliamentary votes to adjourn early.

And regardless of whether or not Mr Martin's government survives, his tenure as prime minister will continue to be overshadowed by the so-called sponsorship scandal.

The opposition Conservatives and Bloc Quebecois have made the corruption scandal their main issue in attempting to topple the government

In February 2004, the country's auditor-general issued a report which said that in the late 1990s, the governing Liberals had channelled at least C$100m (�43m) from a C$250m (�107m) government programme to Liberal-friendly advertising agencies in the primarily French-speaking province of Quebec, for little or no work.

The fund was launched, by Mr Martin's predecessor as prime minister, Jean Chretien, supposedly to promote federalism and national unity in Quebec, shortly after the province voted in a 1995 referendum, to stay in Canada by only the slimmest of margins.

Canadians have been shocked by the explosive revelations coming out of a televised daily public enquiry, the most serious of which suggests the Liberal party accepted kickbacks from the advertising agencies to fund election campaigns

Mr Martin was the country's finance minister at the time of the sponsorship programme. He has strenuously denied any involvement or knowledge about it.

Nevertheless, polls have shown a great deal of public anger directed at the Liberals.

The opposition Conservatives and Bloc Quebecois have made the corruption scandal their main issue in attempting to topple the government.

If Mr Martin's government survives the vote, he has promised to hold an election within 30 days of the public enquiry looking into the corruption allegations publishing its final report, which is expected by the end of the year.