MONTREAL — The federal Liberals are wasting their time trying to persuade the New Democrats to form an alliance of so-called left-wing forces in an attempt to take power back from Stephen Harper's Conservatives, says NDP Leader Jack Layton.

In an interview with a Montreal newspaper, Layton said the Liberals are far from a left-wing party and that the sponsorship scandal has tarnished the party's image for a long time to come, especially in Quebec.

Layton added that the NDP risks sabotaging the gains the party has made in Quebec and the rest of Canada if it aligns itself with the Liberals.

Last week, several Liberal leadership hopefuls - notably former Ontario NDP premier Bob Rae and former Harvard professor Michael Ignatieff - called on "progressive forces" to unite in order counter Harper's government.

"To unite things, there has to be a similarity between those things," Layton told a newspaper in an interview published Saturday.

"I don't find the Liberal party to be a left-wing party. From time to time, they take on a left-wing facade. But if you examine its policies and its record while in power, it's not left-wing.

As examples, Layton pointed to Pierre Trudeau's controversial decision to invoke the War Measures Act during the October Crisis of 1970 and large corporate tax cuts under the governments of Paul Martin and Jean Chretien.

The NDP leader also said he isn't attaching much importance to the Liberal leadership race.

"The Liberal party leadership race can't be considered something serious," he told the French-language daily. "People look at the race like it's a soap opera."

Last May, the NDP agreed to support Paul Martin's minority government in exchange for increased spending on social and environmental programs in the Liberal budget.

But Layton told a newspaper that during their last months in power, he realized the Liberals lacked vision.

The NDP eventually withdrew its support for the Liberals, triggering January's election that saw the Tories take power for the first time since 1993.