At first blush, the Parti Québécois and the federal NDP are natural allies, with their left-leaning politics and dislike of the Conservative government in Ottawa.

Instead, tensions between the PQ and the NDP have been growing since Pauline Marois took office last September, even though the two parties share similar power bases in Quebec.

While the PQ government has laid out a number of beefs with the Conservative regime in Ottawa, it is also increasingly bitter at the lack of co-operation that it has received from the NDP and its large contingent of Quebec MPs.

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"The NDP is absent from the major files for Quebec," PQ Intergovernmental Affairs Minister Alexandre Cloutier said in a recent interview this week.

Mr. Cloutier is particularly angry at the NDP support for federal loan guarantees to a hydro-electrical project in Labrador, despite the opposition of the Quebec government. He pointed to other files on which he feels the NDP has not been vocal enough, such as the province's efforts to repatriate the data on long-gun owners from the now-defunct federal registry.

NDP officials are trying to play down the number of conflicts with the PQ, while stating the fact that New Democrats nearly wiped out the Bloc Québécois in the 2011 election has created ill will among some sovereigntists.

"We are not waging open warfare, but we do have some different objectives, and the PQ has its own ultimate objective," said NDP Leader Thomas Mulcair's principal secretary, Karl Bélanger. "The door is always open for discussions on the different files."

The tensions highlight a power struggle between two parties trying to position themselves as defenders of Quebec's interests ahead of coming elections. The PQ is hoping to improve on its minority status in the next provincial ballot, while the NDP wants to at least hold on to its 58 seats in the 2015 federal vote.

Mr. Mulcair and the PQ Leader are set to hold their first meeting in early February, five months after Ms. Marois became Quebec Premier. The two know each other well, having crossed swords in the 1990s and early 2000s when Mr. Mulcair was an opposition Quebec Liberal MNA and Ms. Marois a senior PQ minister.

The main flashpoint between the PQ and the NDP these days is Ottawa's decision to award $6.4-billion in loan guarantees for the Muskrat Falls hydroelectric project in Labrador. According to the PQ, the loan is an affront to Hydro-Québec, which has financed its own mega-projects over the years. Provincial parties in Quebec largely oppose the deal, leading Mr. Cloutier to chastise the NDP for failing to uphold the provincial consensus on the file.

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"The NDP has stood silent, and even supported the project, which is particularly surprising to us," he said.

The NDP offered its support for the loan guarantee for the Muskrat Falls project before the 2011 election, and Mr. Mulcair came out in favour of the deal in the 2012 NDP leadership race. Mr. Bélanger said under the NDP's pan-Canadian vision, the Muskrat Falls project is a worthy green-energy initiative, and that Quebeckers approved that vision in the past federal election.

"We have a legitimate mandate to defend our position," he said.

The PQ government has other disputes with Ottawa, including the government's recent decision to renew a $250-million program for the Canadian auto industry, which is based mainly in Ontario. Mr. Cloutier said the funding is inappropriate given that requests for help for Quebec's forestry industry have largely gone unheard.

The NDP, on the other hand, agrees with the funding to the automobile industry, and says that it will continue to push separately for adequate funding to the country's softwood lumber industry.

The PQ is also angry at recent changes to employment insurance that penalize workers in seasonal industries, which stand to have a large impact in Quebec's outlying regions. The NDP has also objected to recent EI reforms, but it will not back the PQ's request for the repatriation of the program into the provincial fold.

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While the PQ has harsh words for Conservative policies, relations between the two governments have been cordial, in large part through an effort by the federal government to avoid fuelling flag wars with the PQ.

Mr. Cloutier travelled to Ottawa for his first official visit in mid-December, where he held meetings with Intergovernmental Affairs Minister Peter Penashue and Industry Minister Christian Paradis, who is the government's Quebec lieutenant.

By contrast, Mr. Cloutier failed to secure any time with the NDP, whether with Mr. Mulcair or any members of the party's Quebec caucus.

With a report from Rhéal Séguin in Quebec City