Prime Minister Stephen Harper claimed Wednesday that opposition parties are bent on taking power in Ottawa if a minority government elected, a thesis that one expert says will likely underlie Conservative attack ads for the rest of this campaign.

Speaking to reporters in Quebec on Wednesday morning, Harper said that "if they have a minority Parliament, they will in some manner try and get together and form a government."

The Conservative leader said these rival parties would effectively create a government that doesn't know what it stands for, nor how it will operate once in power.

"We don't know what its program will be, they'll negotiate that later," Harper said.

"We do know that everything they are talking about points to higher spending and tax hikes. It points to renewed fighting over referendums, constitutions and national unity. That's what it all points to."

Harper said these parties have "no clear plan on the economy, no clear plan for job creation."

He urged Canadians to reject the scenario he outlined by giving the Conservatives a majority government.

Harper's remarks came a day after Liberal Leader Michael Ignatieff said he would be willing to try to form a government with fellow opposition parties if the Tory leader wins the most seats in the election but fails to win the confidence of the House of Commons.

During an interview on Tuesday, Ignatieff said that "if the Governor General wants to call on other parties, or myself, for example, to try and form a government, then we try to form a government."

Media consultant Barry McLouglin said the Tories are likely to push the coalition controversy in the final days of the campaign, as they try to persuade the electorate that a Conservative majority is the best option for Canadians.

"The gloves have to be off. This is now a do-or-die majority government situation for Stephen Harper and the Tories," McLoughlin told CTV's Canada AM during an interview from Ottawa on Wednesday morning.

McLoughlin said the Conservative leader will use Ignatieff's words as "firepower" to raise the issue of who the voters should expect to be their prime minister.

"I think for the average person, they are going to be confronted now with who am I ultimately going to see as prime minister of this country and who are the key influences on him?" said McLoughlin.

Recent polls from Nanos Research conducted for CTV and The Globe and Mail suggest that the Conservatives, NDP and Liberals hold roughly the same level of national support that they did at the start of the campaign.

The latest Nanos Research poll results released Wednesday put the Tories at 39.1 per cent support, compared to 37.6 per cent at the start of the campaign. The same poll said the Liberals currently hold 28.4 per cent (compared to 26.2 per cent when the election was called) and the New Democrats 19.8 per cent (compared to 18.2 per cent).

Alex Sevigny, an associate professor of communications at McMaster University, said this lack of movement in the polls can be a challenge for opposition parties trying to woo voters who are still undecided.

"There is a potential suppressive element to polling," Sevigny told CTV's Canada AM during a telephone interview from Hamilton on Wednesday morning.

"And that is that people who would normally vote for an opposition party may be discouraged," Sevigny said, such as in the case of possible Liberal or NDP voters who don't believe the opposition can defeat the government in the face of the polls.

Sevigny said these opposition parties have to work harder to get their supporters out on Election Day, as compared to the government, which already has a committed support base to rely upon.

But for all the parties jockeying for an advantage out on the hustings, "the undecideds are where it's at right now," said Sevigny, because these are the voters that can help turn vulnerable ridings into parliamentary seat gains.

With files from The Canadian Press