Quebec Premier Jean Charest is suing former justice minister Marc Bellemare over his claims that Charest was aware that Liberal Party donors were influencing the selection of judges in the province.

In a lawyer's letter sent Tuesday, Charest's lawyers asked Bellemare to retract his comments by 4 p.m. Wednesday or they would pursue legal action. The letter accuses Bellemare of making false, defamatory allegations that were widely reported in the media and harmed Charest's reputation.

The premier said he plans to sue for $700,000 in punitive damages for defamation.

Earlier this week, Bellemare rocked Quebec's political world when he told CBC's French-language service that when he was justice minister, he was pressured on three separate occasions to appoint specific judges favoured by influential Liberal donors.

Quebec Premier Jean Charest, shown at the national assembly on Tuesday, is suing his former justice minister, Marc Bellemare, for defamation. (Jacques Boissinot/Canadian Press)Bellemare, who served in Charest's cabinet from 2003 to 2004, said he was cornered by a prominent Liberal fundraiser and complained to Charest about it twice — in the fall of 2003 and in the spring of 2004.

Charest has denied that Bellemare ever discussed the matter with him.

Charest also announced Wednesday the appointment of former Supreme Court justice Michel Bastarache as head of a provincial public inquiry into the judge nomination process.

Bastarache is expected to file a report by Oct. 15, Charest said.

Bastarache, 62, was a member of Canada's highest court between 1997 and 2008.

Gomery declines comment on politics

Bellemare also alleged that construction company bosses stuffed Liberal coffers with generous cash donations. In recent months, Quebec's construction industry has been buried in allegations of corruption.

The Opposition Parti Québécois has already demanded a wider inquiry into Liberal Party fundraising and the construction industry. After Bellemare's allegations, the PQ tabled a motion calling for retired federal justice John Gomery, who headed the probe into the federal sponsorship scandal, to oversee any inquiry.

Gomery, who was recently appointed president of Quebec's Press Council, said in a statement he will not weigh in on any political matter during his tenure at the watchdog association.

Charest's popularity at a low

Charest is not in any immediate threat of a downfall since the Liberals easily defeated the PQ and Action Démocratique du Québec in the December 2008 provincial election. But his Liberal government has never been so unpopular.

Marc Bellemare, shown in 2004, rocked Quebec's political world this week when he suggested he was pressured as justice minister to name judges favoured by influential donors to the Liberal Party. He alleged Charest knew but did nothing to stop the influence peddling. (Jacques Boissinot/Canadian Press)

A Léger poll for Montreal newspaper Le Devoir suggests the Liberals have just 30 per cent public support, compared with 40 per cent for the PQ.

Fully 77 per cent of respondents said they were unhappy with the government, according to the poll, which was published on Monday.

That's a record-high rate of dissatisfaction, and the poll was conducted before Bellemare's explosive allegations, said Léger vice-president Christian Bourque.

Charest is facing dark days ahead, Bourque suggested.

"This is the first time that something is attacking [Charest's] honesty or his perceived honesty with the public. It is the first time that it is directed at him," he said.

"This is probably the toughest crisis that he has ever faced."

With files from the CBC's Tim Duboyce, the Canadian Press, Reuters