OTTAWA - Prime Minister Stephen Harper has no plans to take up Mario Dumont's offer to re-open the Constitution, one of his top lieutenants said Monday.

"Our focus is on concrete, tangible deliverables, not abstractions,'' Jason Kenney, secretary of state for multiculturalism and Canadian identity, said in an interview.

Over the weekend, Dumont, Quebec's new leader of the Opposition, said he's ready to launch negotiations aimed at securing Quebec's signature on the Constitution. He suggested the province could sign on if Harper agrees to enshrine limitations on the federal spending power.

"If Ottawa is ready to open the debate on spending power, (Quebec's) National Assembly should have an initiative to facilitate its inscription in the Canadian Constitution,'' Dumont said Saturday.

A spokesman for Harper declined to comment on Dumont's overture.

However, in last month's budget, Finance Minister Jim Flaherty reconfirmed the Harper government's commitment to limiting the federal spending power. He promised to focus new spending primarily on areas of federal jurisdiction and refrain from intruding on provincial areas of responsibility.

Flaherty promised that no new cost-shared programs in areas of provincial jurisdiction will be created without the consent of a majority of provinces. And he said provinces could opt out of such programs, with federal compensation, provided that they offer similar programs.

But the budget also hinted that Harper might be prepared to go further. It said the government "will continue to further clarify roles and responsibilities'' of the federal government and will explore with the provinces ways to "formalize'' its promise to limit the federal spending power.

Kenney said he's not sure what Flaherty meant by the word formalize. But he added: "It's a general policy approach of our government not to interfere in areas of provincial jurisdiction and we would certainly have no objection to making that as a formal policy statement in some fashion.''

Asked if it could mean a constitutional amendment to limit the spending power, Kenney said: "Not so far as I know.''

The Harper government floated the idea of constitutionalizing limits on the spending power last year. But the response from premiers was tepid to outright hostile.

Still, dabbling in constitutional matters might be tempting to Harper. The political rewards, should he succeed in gaining Quebec's signature on the Constitution, would be huge.

He'd be able to boast that he'd accomplished a feat that has eluded every prime minister since Pierre Trudeau patriated the Constitution in 1982 over the objections of Quebec's then-separatist government. Having plucked the thorn that's caused so much pain to the Canadian federation, he'd also be justified in boasting that the Conservatives are the party of national unity, a moniker claimed by the Liberals for decades.

University of Windsor political scientist Heather MacIvor said Harper's commitment to reform the Senate could be another  inducement to reopening constitutional negotiations. She pointed out that Harper has gone as far as he can outside the Constitution to overhaul the Upper House, introducing legislation to elect senators and limit their terms to eight years.

With Harper's core constituency in Alberta upset with the Tories' flip-flop on taxing income trusts and its big-spending budget, MacIvor said Harper may conclude that comprehensive Senate reform "may be a way to throw them a bone.''

Still, MacIvor doubted the potential rewards are tantalizing enough to counterbalance the enormous risks entailed launching another round of constitutional negotiations, which in the past have quickly bogged down in fruitless, divisive wrangling.

"The big question is, is it worth it? You have to know before you even open this up that everybody's going to pile in, everybody's going to have their own pet agenda,'' she said.

As happened in the failed Meech Lake and Charlottetown constitutional negotations, any attempt to satisfy Quebec's demands would inevitably prompt objections from other provinces, which would come up with their own list of demands.

"Everybody's going to have their quid pro quo,'' said MacIvor.

Even if negotiations could be confined strictly to the spending power, agreement among the provinces wouldn't be likely. The smaller have-not provinces have a vested interest in maintaining a strong central government and have never been keen to constrain its spending power.

And -- thanks to former prime minister Jean Chretien's legislation giving a veto to each of the country's five regions --  MacIvor noted that amending the Constitution has become almost impossible without unanimous provincial consent.

McGill University political scientist Antonia Maioni said there "might potentially be an upside in Quebec'' to reopening the Constitution with an eye to getting the province to finally sign on.

"It's no secret that every political party in Quebec thinks this is unfinished business,'' she said.

"I think the big risk for Stephen Harper is how it plays in the rest of Canada and that's where the challenge is.''

Given the risks, Maioni doubted Harper would wade into the constitutional fray anytime soon.

"I'm sure it's not something that Stephen Harper thinks is politically manageable in the short term,'' she said.

Moreover, Maioni said he'll want to avoid responding to Dumont's overtures for fear of upsetting Jean Charest, who is still the Liberal premier of Quebec, albeit with a minority government.

Chretien, justice minister who shepherded the patriation of the Constitution with a Charter of Rights 25 years ago, downplayed the importance of Quebec's refusal to sign on.

"It might be that they will never sign it. But there is one clear reality: they are using it,'' Chretien told CBC Newsworld, noting that even former separatist premier Lucien Bouchard used the constitutional amending formula to reform the province's education system.

"It's as good as signing. Because if it's a matter of principle, they don't use it.''