QUEBEC - Jean Charest's government is expected to survive, but just barely, a non-confidence vote designed to demonstrate how weak the once-popular premier has been rendered by allegations of scandal.

On a day when corruption-related controversies forced two Quebec mayors and one high-ranking provincial official to resign from some of their duties, Charest's opponents moved to bring him down next.

They said they would table a confidence motion next Wednesday, when the premier is in Europe, possibly with two of his cabinet ministers.

Suddenly the Liberals, who just last year were cruising along in public support after having been elected to a rare third straight term, seem somewhat vulnerable.

Charest's party holds 65 of the legislature's 125 seats. His government could be toppled by a few resignations, floor-crossings, holdouts, or even a poorly timed snowstorm. The government holds 64 votes, minus the Speaker; opposition parties and Independents hold 59; one seat is vacant.

The Liberals' party whip confidently declared they had the votes to win any confidence showdown.

But the Opposition expressed hope that a few votes might be shaken loose this weekend when elected Liberals return to their ridings and receive an earful from citizens demanding a public inquiry into allegations of corruption in the construction industry.

The few organizations that had supported Charest's refusal to call the inquiry dropped their backing this week.

Montreal newspapers carried front-page headlines Thursday describing the premier's plight.

Charest Painted Into a Corner, read one.

About-Face Isolates Charest, blared another.

One newspaper carried a graphic showing two columns: a "For'' column with a list of organizations demanding a probe, and an "Against'' column containing only one entry: "The Charest government.''

"The premier finds himself totally isolated today,'' Parti Quebecois Leader Pauline Marois told the legislature Thursday.

"Everything's falling apart around him.''

For over a year, corruption has been just about the only major political story in the province.

A spray-gun of allegations has been fired in multiple directions all week, and the accusations of impropriety intensified Thursday.

The head of a Quebec anti-corruption unit was forced to step aside over allegations of crooked financial reporting _ which he denied.

The mayors of Laval and St-Jerome stepped down from the province's union of municipalities over allegations of wrongdoing. The St-Jerome mayor, Marc Gascon, was head of the union. Gascon is accused of having improper dealings with construction companies that got municipal work.

In Ottawa, the federal Conservatives even demanded the resignation of a Bloc Quebecois MP who claimed to be a whistle-blower.

The Tories say Serge Menard shouldn't have waited 17 years to come out publicly with his claim that Laval's mayor offered him a cash-stuffed envelope in 1993.

The most surprising controversy of the day, however, might have involved the head of Transport Quebec's anti-collusion unit.

Former Montreal police chief Jacques Duchesneau, a member of the Order of Canada and a one-time head of the Canadian Air Transport Security Authority, has temporarily left his post.

He had been leading a unit tasked with examining reports of bid-rigging in public infrastructure contracts.

Such allegations have been at the heart of a year-long controversy involving construction companies, well-connected businessmen, and crime groups like the Mafia.

Duchesneau agreed to step aside following a newspaper report that he persuaded a political organizer, when he was running to become Montreal's mayor a decade ago, to provide false financial paperwork.

Duchesneau says he will fight for his reputation.

"I refute the allegations made against me,'' he said in a brief statement before leaving a news conference without taking any questions.

''I am even outraged by them. I cannot accept that my reputation would be sullied so gratuitously. . .The mandate handed to me by the government requires me to be above reproach when it comes to perceptions."

Duchesneau had reportedly persuaded his campaign organizer, in 1999, to put his name to loans he didn't make. The method was reportedly used to direct at least $20,000 to Duchesneau's political party.

Quebec electoral law forbids loans to political parties above $10,000. Duchesneau had lost in his bid to become mayor in 1998 and, the organizer says, he wanted to quickly pay down his campaign debts.

The Charest government explained that it called Duchesneau on the carpet Thursday morning to hear his version of the story.