An insurgent left-wing party with all the momentum in the Quebec election campaign is being accused of having a hidden Marxist agenda – rhetoric reminiscent of the Cold War and a sign of the rising political tension in the province.

Québec solidaire still sat in fourth place six days before the Monday vote, but as the only party surging in polls and with long-term goals to nationalize banks and the mining industry, along with dramatically increasing taxes and spending, the 12-year-old party is getting a new level of scrutiny. Even if it were to win just a handful of seats, the party could wield substantial influence with a probable minority government.

The latest poll, a snapshot conducted by Ipsos over the weekend and published Tuesday, showed Philippe Couillard’s Quebec Liberal Party tied with the Coalition Avenir Québec under François Legault at 30-per-cent support each.

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The CAQ has lost six percentage points of support since the campaign began a month ago, almost mirroring the five-percentage-point rise of Manon Massé's Québec solidaire. The Ipsos poll showed QS at 16-per-cent support, just four points behind the Parti Québécois.

The combined internet and telephone survey of 1,250 people has a margin of error of 3.2 per cent 19 times out of 20.

“It would be extremely surprising if anyone pulled off a majority with numbers like that,” said Sébastien Dallaire, the general manager of Ipsos Québec. “With these numbers, the CAQ would be most likely to win.”

The poll showed the CAQ holding a sizable advantage among francophone voters, who form the majority in swing ridings. But polling expert and sociologist Claire Durand cautioned that the Liberals traditionally see a bump from “discrete” voters on election day that polls rarely capture.

With most of the parties’ promises announced, the campaign has settled into a sniping match as all four parties try to motivate their supporters to cast their ballots.

In a 24-hour sampling, Mr. Couillard accused Mr. Legault of trying to hide from journalists and their questions; Mr. Legault accused Mr. Couillard of hiding assets in offshore accounts; and Parti Québécois Leader Jean-François Lisée accused Québec solidaire of having a secret Marxist agenda. None of the accusations came with much evidence.

Mr. Lisée, whose pro-independence, progressive party could also hold much influence in a split legislature, has ramped up attacks in recent days that QS is too extreme. “Québec solidaire is anchored in Marxism and anti-capitalism and is controlled in secrecy by a dogmatic, sectarian current,” he said.

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Ms. Massé, the co-representative of QS, which has an unusual dual-headed structure shared with Gabriel Nadeau-Dubois – the leader of Quebec’s massive 2012 student protests – added fuel to the fire when she appeared to accept the label in a TV interview before shying away from it Tuesday. “I refuse to get into this kind of mudslinging and I’m not really into labels,” she said. “I care about people. Mr. Lisée is trying to scare people.”

QS maintains that many of its nationalization plans remain long-term policy objectives. In the short term, it promises to have the province take over the tax-free savings account system and mandate that a portion of the funds be dedicated to loans for green renovations. It would also raise about $12.9-billion in revenue by the fourth year of a mandate by, among other measures, increasing taxes on corporations and personal income above $97,000. It would spend $10-billion on Montreal transit over four years.

The rise of QS, with its orange campaign materials and left-wing politics, has reminded some commentators of the NDP’s Orange Wave in 2011 under Jack Layton, which saw the party rise from obscurity to take a majority of seats in Quebec.

“What we’ve seen in the past few elections, especially at the federal level, is voters are very willing to move from right to left or back without seeing a contradiction,” Mr. Dallaire said. But provincially, the Liberals and PQ have die-hard supporters that are unlikely to roll in a wave. “Québec solidaire and its players are more of a known quantity in Quebec than Jack Layton was. There is not likely to be such a big wave of love for these people.”