TORONTO - Several labour groups are warning the minority Liberals they may not be able to count on union support if their budget is defeated next week, triggering another election.

"(Premier Dalton) McGuinty has to know, if he wants to call an election, that all those people he has relied upon he has now ticked them off in a major way," said Sid Ryan, president of the Ontario Federation of Labour.

"I don't see them on the telephone banks, and I don't see them on the riding associations, knocking on doors to help the Liberals get elected."

His group launched a campaign against the Liberal budget Friday, saying proposed service and job cuts are the biggest since the era of former Tory premier Mike Harris.

The province has seen eight years of labour peace under McGuinty, who has prided himself on maintaining good relations with unions.

But as his cash-strapped government grapples with a massive deficit, it has come down hard on the unions, proposing -- and threatening to legislate -- public wage freezes.

The Elementary Teachers' Federation lashed out at the government last week for publicly chastising it for walking away from a voluntary process to help guide upcoming negotiations.

That same day, a group representing Ontario's doctors expressed concern over the freeze they say could leave them with 16 per cent less pay. That calculation is based on increases they had expected to receive in return for doing extra work.

The Liberals have said they want to work with the unions, but that everyone will have to do their part to help the province get out of the red.

Ryan said the concern isn't just about wage freezes, but rather about allowing free collective bargaining. That goes beyond wages and includes benefits, working conditions and health and safety -- all things he now considers in danger because the government is telling unions to accept its proposal or face legislation.

"That essentially is saying to folks: 'Your charter rights only exist in good times, and in bad times we will take them away,"' said Ryan.

The group, which includes more than 90 labour and community organizations, will gather at the Ontario legislature Saturday for a rally, followed by a march through the city's high-end shopping district of Yorkville.

It plans to protest what it calls unfair budget cuts that target poor and middle-class families.

NDP Leader Andrea Horwath, who is in negotiations with the Liberals to possibly prop up the government in Tuesday's vote, said she wouldn't be surprised to see a large group at the rally because of people's "sheer frustration with a budget that simply is not fair."

"(The unions) are pretty frustrated with the way the government has dealt with the situation of collective bargaining," she added.

"Legislating wage freezes doesn't work."