MONTREAL - Tonight Quebecers will get to see the second of four back-to-back election debates.

Premier Jean Charest will square off against Parti Quebecois Leader Pauline Marois, who is leading in the polls and is currently considered the front-runner to replace him.

The province is experimenting with an unconventional debate format in the runup to the Sept. 4 election.

There are a series of one-on-one contests. After tonight's event there will be another small debate tomorrow, involving Charest and Francois Legault, leader of the new Coalition party.

Then finally Legault and Marois, who are former cabinet colleagues, will face off against each other Wednesday.

The only debate featuring all the main party leaders on the same stage occurred last night.

Marois, who could be elected as Quebec's premier in two weeks, used the event to repeatedly attack Prime Minister Stephen Harper, in a hint of federal-provincial battles that might follow the Sept. 4 vote.

From her opening remarks, and throughout the Sunday debate, Marois highlighted her strategy of confrontation with the Harper Tories.

The PQ leader did not even make a reference to her party's raison d'etre, Quebec independence, in the opening remarks but she did refer to the prime minister.

"I will never let Stephen Harper choose for us," Marois said Sunday, in a reminder of spats with the Tories over employment insurance, justice policy and transfer payments.

"I won't get on my knees before Ottawa like Charest does. And I won't renounce the fight, like Legault."

The PQ has said that if it's elected it will seek a transfer of powers from Ottawa in areas like employment insurance and immigration policy. The party says it will use each refusal from the Tories to build its case that Quebec doesn't belong in Canada.

One of the other debate participants wondered, however, why the PQ leader was so timid about talking about her plan for independence.

In fact that opponent, the co-leader of Quebec solidaire, Francoise David, discussed her own ideas for achieving independence more explicitly than the main sovereigntist leader.

David's party has not been invited to participate in the one-on-one debates starting Monday.

With one opportunity to connect with a TV audience, in Sunday's debate, David quipped during an exchange with Marois: "Attacking Harper is easy. Just about everyone in Quebec can't stand him."

It wasn't the only sign of David's effort to steal votes away from the PQ base. She was wearing the red-square symbol of the student protest movement.

This was in contrast to Marois, who has stopped wearing that square. As for the student protests, which had dominated political discussion for months, they rarely came up Sunday.

Marois sought to reassure her independentist base and insisted that she would hold a sovereignty referendum "tomorrow morning," if she felt she could.

With his political survival in doubt, Charest used a two-birds-with-one-stone attack.

He kept reverting to themes that could harm both his main rivals simultaneously: doubts about Quebec independence, and alleged ethical misdeeds of the last PQ government.

Charest said neither of his rivals could be trusted on the independence issue. Some of his most pointed remarks were aimed at Legault, the former PQ minister and now leader of the new Coalition party.

"For 40 years of your life you weren’t just an ordinary sovereigntist… you were the most aggressive of the group," Charest said to Legault. "For 40 years you were a sovereigntist. Now for four seconds, you change your mind."

The theme of Legault's abrupt conversion was also raised by his former colleague, Marois, who recalled Legault's once-burning desire to achieve independence. Legault replied that, like many Quebecers, he had simply gotten fed up with a debate that was going nowhere.

"I don't see anyone, on the ground, asking about a referendum," Legault said. "I'm not seeing battles on Montreal buses about a referendum."

On ethics issues, Charest burst into attack mode and targeted nearly everyone.

Battered by two years of scandals, the premier fired back by repeatedly referring to a six-year-old report that described illegal fundraising schemes in the Parti Quebecois government of 1994 to 2003.

As it happens, Charest's two main rivals in the election — Marois and Legault — belonged to that PQ government.

The Liberal premier urged viewers to go online and view the report. He even levelled an allegation of an improper donation to Marois' leadership campaign, with $2,500 from a teenager.

"There's only one case that's been proved, while you're making all kinds of insinuations (about my government)," Charest said.

"There's one proven case of a government that closed its eyes — and that's the government of which Pauline Marois and Francois Legault were a part... as proven in the Moisan report."

Charest was referring to a report, released by the province's elections watchdog in 2006, that described the PQ improperly receiving $96,400 from the Groupaction marketing firm. The company was best known for its role in the federal sponsorship scandal.

The 2006 report also concluded that the company, through its employees, also donated $8,325 to the Liberals. Corporate donations to parties have been illegal in Quebec since the 1970s.

In recent years the Liberals have been battered by scandals over their finances — including the high frequency of donations from employees at engineering firms.

There are also reports of Liberal donors receiving lucrative permits for day-care spaces. The minister once responsible for the day-care program, Tony Tomassi, has been forced to quit politics and now faces criminal charges over his use of a credit card supplied by a company that received government business.

"Did you find that normal?" Marois told Charest.

She reminded the premier that when the first controversies surfaced involving Tomassi, his Liberal colleagues would rise to cheer him as he was being attacked in the legislature: "You were getting up to applaud him," Marois said.

Quebec's provincial campaign entered a new phase Sunday with the first in a string of televised leadership debates. There are four debates on four consecutive nights, giving voters a chance to better weigh their options.

Sunday's was the only debate that will include all four leaders of the biggest parties — while the remaining ones will feature a series of one-on-ones. The four topics Sunday were: the economy, governance, social policy, and the national question and identity.

In Sunday's debate, a frequent theme was attacks on the trustworthiness and preparedness to govern of Legault's new party.

Charest joked that the former PQ cabinet minister couldn't be trusted on the most fundamental of questions. He referred to Legault's recent statement that he would vote against Quebec independence in a referendum — a statement that stunned some of his old allies.

But Legault replied that the premier was mired in "old battles," playing a tired old tape. He accused his opponents of being obsessed with independence talk and said they were focusing on issues people no longer cared about.

"We will show the door to career politicians," Legault said, during his opening statement.

"It's enough… Things need to change."