Prime Minister Pierre Trudeau last night called a general election for May 22 in a bid to lead an increasingly troubled Canadian federation for another five-year term.

After 11 years in power, the 59-year-old Trudeau appears to be facing an uphill battle amid growing voter dissatisfaction with Canada's ailing economy and Quebec's drive for independence that is casting doubts on the future of the federation.

In a brief statement last night, Trudeau set out his campaign theme that included maintaining Canadian unity and generating economic prosperity.

"My message to you tonight is that we Canadians have an unparalleled opportunity -- working together -- to shape with our own hands an ever freer, richer, more secure Canada for ourselves and for our children," Trudeau said.

The most recent public opinion polls show Trudeau's Liberal Party running neck-and-neck with the opposition Progressive Conservative Party, led by Joe Clark, 39.

Trudeau was swept to power in 1968 on a platform of "national unity," aiming to bridge the historic chasm between the English-speaking majority and the 27 percent of Canada's 23 million citizens whose mother tongue is French.

But 11 years later, Trudeau's native province, predominantly French-speaking Quebec, is ruled by a separatist government whose objective is to make Quebec an independent country.

A public opinion poll published Sunday indicated that a majority of Quebecers are now prepared to back the provincial government of Premier Rene Levesque, which is seeking a mandate to negotiated sovereignty for Quebec in economic association with the rest of Canada.

Levesque's Parti Quebecois plans to hold a referendum on sovereignty-association. It could take place as early as next fall.

Apart from the Quebec problem, which has become one of the main preoccupations of Canadians, Trudeau has been forced to defend his policies almost daily in the face of the deterioration of the once-robust economy, which now suffers from high inflation, the highest unemployment rate since the Depression and a weakenning of the Canadian dollar. It now stands at U.S. $0.85.

Moreover, the federal government has been in continuous conflict over the control of natural resources with the mineral and oil-rich western provinces.

With recent setbacks and defections, the current party standings in Parliament are Liberals 133, Conservatives 98, New Democratic Party 17, Social Credit 9 and 5 independents. There are two vacancies.

Because of the redistricting, the new Parliament will have 282 seats, an increase of 18.

Seeking to reshape the Canadian constitution and forge a new sense of national unity, Trudeau has gone a year beyond the normal four-year span and was three months away from the mandatory limit when he called the election.

The Liberals, who have won the last five elections, have governed Canada for 36 of the last 43 years. The last Conservative government, led by John Diefenbaker, was in power from 1957 to 1963.