OTTAWA - Quebec is prepared to go to court if necessary to stop Prime Minister Stephen Harper's plans to reform Canada's unelected Senate, the province's intergovernmental affairs minister says.

Benoit Pelletier issued the warning Friday just as support appears to be building among western provinces to turn the Senate into an elected chamber.

"I would say that the main goal for us as for now is to stop Bill C-20,'' Pelletier told The Canadian Press.

C-20, currently under review by a House of Commons committee, would create a process for electing senators. The federal government, backed by some of the country's foremost constitutional experts, maintains the bill needs only the approval of Parliament to become law.

But Quebec, backed by constitutional experts of its own and several other provinces, maintains such a significant change to one of the country's primary political institutions can only be done with a formal constitutional amendment approved by at least seven provinces representing 50 per cent of the population.

Pelletier said the province still hopes to persuade Harper to refer the matter to the Supreme Court of Canada, something the prime minister has so far refused to do. If Harper refuses to budge, Pelletier said the Quebec government is considering taking matters into its own hands, asking the province's court of appeal to rule on the issue.

"If ever the federal government goes ahead with its intentions then we will very closely study the possibility to go before the tribunals ourselves on that question,'' he said in an interview.

"We are analysing at this moment the possibility to go ourselves before the tribunals.''

Pelletier noted that at least three other provinces -- Ontario, New Brunswick and Newfoundland and Labrador -- agree with Quebec's contention that the federal government is proceeding in an unconstitutional manner.

While there have been no formal discussions with other provinces yet, he said he expects Quebec would have strong allies should it decide to take the matter to court.

In Ontario, an official said the government continues to believe that "the changes being introduced by the feds require the consent of the provinces.''

Moreover, the official said Premier Dalton McGuinty remains uninterested in Senate reform, preferring to focus on "helping families and businesses through the challenges caused by the slowing U.S. economy.''

But if the prime minister is determined to push ahead with Senate reform, the official said, McGuinty would prefer to abolish the chamber altogether.

The increasingly adamant resistance to an elected Senate in the country's two largest provinces counterbalances some modest signs of progress in western Canada.

This week, Saskatchewan signalled that it will follow Alberta in setting up a process to elect senators. Manitoba announced it plans to launch provincewide consultations this spring on the best way to elect senators. And British Columbia Premier Gordon Campbell signalled he's prepared to support Harper's Senate election bill, provided there's no cost to the province.

Since taking power two years ago, Harper has made only two Senate appointments -- Michael Fortier to boost his cabinet representation from Quebec and Bert Brown, who won a Senate election in Alberta. In an apparent bid to pressure the provinces into supporting C-20, Harper has refused to appoint unelected senators, letting 14 vacancies in the 105-seat chamber go unfilled.

Pelletier said the Quebec government might also consider going to court to force Harper to fill vacant Senate seats, should the vacancy rate eventually make it impossible for the upper house to fulfil its role as the chamber of sober second thought.

"If the seats in the Senate are not filled by new members, eventually it will seriously affect the credibility of that institution and the authority of that institution in our system. So it's a way to do indirectly what in our view cannot be done directly,'' he said.

For now, however, Quebec's priority is to derail the Senate election bill. Pelletier said the depth of his province's concern is reflected in the fact that he has already appeared before one parliamentary committee to press for a Supreme Court ruling on the constitutionality of the bill and made several written submissions.

And he intends to make his case one more time before the Commons committee early next month.

Pelletier said the Senate, intended to represent the provinces in counter-weight to representation by population in the House of Commons, was "part of the essential conditions presiding (over) the birth of Canada.''

As a result, he said the chamber can't be significantly changed without the approval of the provinces.

Quite apart from the process by which Harper is proceeding, Pelletier said Quebec does not support the substance of C-20. Quebec believes senators should be chosen by provincial governments, turning the Senate into a so-called House of the Provinces.