OTTAWA - The Harper government is accusing the Liberals of provoking a constitutional crisis over Senate reform.

The Tories levelled the charge Thursday, one day after the Liberal-dominated Senate moved to shelve a bill imposing an eight-year limit on senatorial terms until the Supreme Court determines whether it is constitutional to proceed without provincial consent.

Peter Van Loan, the government House leader, said the Senate has no constitutional authority to compel the government to seek the Supreme Court's advice on legislation. The authority to refer matters to the top court belongs solely to the federal cabinet, he said.

"If you have a situation where the Senate refuses to carry out its constitutional obligation to deal with government bills and tries to arrogate to itself this kind of power, then you're provoking a constitutional crisis. That's what the Senate is doing here,'' Van Loan said outside the Commons.

He accused Liberal senators of resorting to an "illegal'' ploy in a bid to "protect (their) privileges and avoid Senate reform.''

But Van Loan dodged when asked repeatedly if the government will challenge the legality of the Liberal senators' move. Instead, he professed hope that the Senate as a whole will put a stop to it.

A motion to shelve the bill was approved Wednesday by the Liberal majority on the Senate's legal and constitutional affairs committee. It must still be adopted by the full Senate but, given the Liberals' huge majority in the red chamber, there's little chance the bill can be salvaged.

The ploy does not technically kill the bill nor does it force the government to seek the top court's advice on it. However if the government does not get a green light from the court, the bill will languish in limbo, never proceeding to third reading in the Senate.

During question period in the House of Commons, Van Loan ignored Liberal questions about Prime Minister Stephen Harper's position on climate change at the G8 summit and instead launched into a tirade against unelected, unaccountable Liberals senators.

He accused them of conducting a "brazen usurpation of constitutional power'' and challenged Liberal Leader Stephane Dion to "for once, stand up for democracy and protect Canadian democracy and the Canadian Constitution.''

But Dion endorsed the actions of his Senate colleagues, arguing that they have a duty to ensure that legislation is constitutional. He said they're also duty-bound to respond to the concerns of four provinces -- Ontario, Quebec, New Brunswick and Newfoundland and Labrador -- which all insist provincial consent must be obtained before proceeding with Senate reforms.

"We're speaking about the law of the land, we're speaking about the Constitution of our country and it's legitimate for senators to say don't ask us to support something that may not be constitutional,'' Dion said, noting that constitutional experts are split on the matter.

"The prime minister consulted nobody, no experts, no premiers and he wants to blame the Senate? It is his fault.''

The Liberal senators' manoeuvre was also applauded Thursday by Ontario and Quebec.

Benoit Pelletier, Quebec's minister of intergovernmental affairs, called the move "a wise one'' and urged senators to similarly shelve another bill, C-43, which would create a process for electing senators.

The Tories, backed up by some leading constitutional experts, insist imposing a term limit is a minor change that can be done unilaterally by Parliament. But Pelletier said the bill is clearly part of a package with the Senate election bill and together they constitute "major reform'' of the upper house, requiring the consent of at least seven provinces representing 50 per cent of the population.

Pelletier's Ontario counterpart, Marie Bountrogianni, said the two largest provinces agree that Senate reform should not be attempted in a piecemeal fashion "by end-runs and loopholes.''

"You have to see Senate reform as a whole and that does require opening up the Constitution,'' she said.

While the Liberals and Tories traded barbs over the issue, the NDP condemned them both.

"This was a totally useless piece of democratic reform,'' said New Democrat MP Joe Comartin, calling for "a pox on the Conservative government for taking us down this road; it's a gross waste of time.''

At the same time, Comartin wouldn't give any credit to Liberal senators for putting a stop to it, contending that "they're only concerned about protecting their own jobs."