Prime Minister Paul Martin on Sunday officially opened what is expected to be a bitter national campaign, with polls showing that his Liberal Party may lose its parliamentary majority in voting set for June 28.

Martin warned Canadians that Stephen Harper, the leader of the Conservative Party, would destroy Canada's social programs with a platform to lower taxes to the level of those in the United States.

Harper answered the criticism minutes later, accusing the Liberal Party, which has governed the country since 1993, of creating a campaign of fear. "You know, in this country," Harper said, "you can be Canadian without being a Liberal."

"I know the arithmetic of the tax-cutting equation," Martin said at a news conference in Ottawa. "You cannot have social programs like Canada with taxation levels like those of the United States."

Martin, who promised to strengthen Canada's public health care system and build Canada's economy, said, "This election is about the kind of Canada we want."

Public opinion polls show voter discontent with a financial scandal in which police say millions of dollars were funneled to advertising firms with close ties to the Liberal Party. Police say little or no work was done in exchange for the payments.

Martin has denied any knowledge of the alleged misuse of funds in the program, which operated while he was finance minister. Last week, opposition parties criticized Martin for shutting down a committee investigation into the scandal before the committee reached conclusions.

"Paul Martin promised there would be no election until there had been accountability for the missing millions," Harper said. "Today that promise has been broken."

Opinion polls released Saturday show the Liberals locked in a tight race with Conservatives for the Parliament. Support for the Liberals had dropped to 35 percent; the Conservatives were at 26 percent and the New Democratic Party was at 18 percent.