Canadian vote could decide carbon tax's future

* British Columbia campaign officially starts

* Seen as test on economy and carbon tax

* Candidates must compete with NHL playoffs

By Allan Dowd

VANCOUVER, British Columbia, April 14 (Reuters) - Politicians on Canada's Pacific Coast hit the campaign trail on Tuesday for the start of a provincial election that could decide the fate of North America's first comprehensive carbon tax.

British Columbia is the first province to hold an election since Canada slid into recession, although polls indicate the governing Liberal Party is headed for another victory over the New Democratic Party when voters cast their ballots on May 12.

NDP leader Carole James called on voters to punish Premier Gordon Campbell's Liberals for mishandling the economic downturn, which has pushed unemployment in the province's largely resource-based economy to 7.4 percent.

"British Columbia has had the worst job losses in the country. We need a change," James told a rally near Vancouver.

The Liberals, who have governed the province since 2001, say the New Democrats mismanaged British Columbia's finances when the economy was doing well in the 1990s and cannot be trusted to handle it now when times are tough.