TORONTO - Ontario Premier Dalton McGuinty is becoming the "small man of Confederation" by demanding 21 additional seats in the House of Commons instead of living up to the province's historic role as a nation builder, the federal government charged Tuesday.

Conservative House Leader Peter Van Loan upped the rhetoric in his war of words with McGuinty over Ottawa's bill to increase the number of seats in Parliament to reflect population growth in Ontario, Alberta and British Columbia.

"Dalton McGuinty seems to be abandoning the traditional role of an Ontario premier, which would see Ontario's interests protected while at the same time advancing the strength of Confederation," Van Loan said in an interview.

"He seems to prefer to become the small man of Confederation, focusing only on taking partisan shots while not concerned about the strength of Canada as a whole."

Van Loan, who represents a southern Ontario riding in the Commons and is also the minister responsible for democratic reform, said the Atlantic provinces, Manitoba and Saskatchewan would all lose seats in Parliament if the government adopted the true "representation-by-population" formula McGuinty seems to support.

The Conservative's Democratic Representation bill would give BC seven new MPs, Alberta five and Ontario 10 - 11 fewer than the province would get if it was being treated the same as the other fast-growing provinces, McGuinty said.

"Prime Minister Harper made the right kind of commitment to put in place a new law governing the number of seats for Alberta, B.C. and Ontario, because we were under-represented in the House of Commons," McGuinty said before a Liberal caucus meeting.

"He's fixing the problem for Alberta, he's fixing it for B.C., but he's only taking half measures with respect to fixing it for Ontario."

McGuinty has been lobbying Ontario MPs to ask them to raise the issue in Parliament, and has been holding talks with federal Liberal Leader Stephane Dion and NDP Leader Jack Layton to enlist their help in getting more Commons seats for Ontario as part of a broad public campaign.

"I'll be writing to all Ontario MPs and asking Ontarians to understand what the feds are about to do, (and) to recognize that this is plainly unfair," he said.

"We're not looking to diminish numbers for anybody else. We're just saying that as our population grows, we should be accorded the same rights as growing populations in Alberta, B.C. and any other province, for that matter."

McGuinty insisted Harper's plans would shortchange Ontario and cannot be justified, but as to whether it's because of a perceived lack of public support for the federal Conservatives in Ontario, the premier refused to speculate.

"All I'm going to say is it's unfair," he said. "We're not asking that any other province have its seat numbers reduced. We're just saying that we should be recognized in the same way that Alberta and B.C. are being recognized."

Van Loan said Tuesday that McGuinty is bent on fighting a bill that would actually improve Ontario's representation in the House of Commons, noting Ontario would get only four more seats in the Commons under the current formula.

"For some reason the premier of Ontario has decided to make his great crusade fighting a bill that treats Ontario better than the existing law," he said.

"McGuinty apparently opposed Ontario doing better, because the choice is not our bill or some hypothetical unreality. The choice is our bill or the existing formula - under which Ontario is badly shortchanged."

McGuinty said he was confident Ontario voters would understand that the province is getting the short end of the stick from the federal Tories.

"What we're talking about is an issue of fundamental fairness that affects all Ontarians," he said.