B.C. Liberal Leader Gordon Campbell's popularity has fallen 12 points in the polls since he won the May 12 provincial election, the latest Angus Reid Strategies poll suggests. (CBC)

The latest Angus Reid Strategies poll suggests the B.C. Liberals' plan to roll out the new harmonized sales tax is driving their supporters into the arms of the opposition NDP.

The results suggested 42 per cent of decided voters would cast a ballot for the B.C. NDP candidate in their riding if a provincial election were held tomorrow. The provincial Liberals were second with 34 per cent, followed by the B.C. Green Party with 12 per cent, and the B.C. Conservative Party with seven per cent.

The Liberals were elected with 46 per cent of the vote in May, but the latest poll suggests they've since dropped 12 percentage points. It also showed Premier Gordon Campbell's approval rating also fell 12 percentage points to 24 per cent.

Mario Canseco, vice-president of public affairs for Angus Reid, said the new harmonized sales tax is the mostly likely cause of the Liberals' declining popularity.

Voters wary of tax changes

"Voters who support the B.C. Liberals tend to be fiscally conservative, and the idea of a new tax or a different way of dealing with taxes is something that they don't like," said Canseco.

The party has come under fire after Campbell made a surprise announcement last month that the province would be rolling out a 12 per cent harmonized sales tax in July 2010. The new tax will replace the provincial sales tax and GST in B.C., but small businesses, restaurants and consumers have raised concerns that the new tax will be applied to many items that were previously exempt from the PST.

Despite the NDP's rising popularity, party leader Carole James' approval rating also fell, from 36 per cent in May to 27 per cent in August. And the 51 per cent of respondents who supported the NDP in the last provincial election said the party should change its leader in the near future.

Angus Reid conducted the online poll of a controlled sample of more than 800 BC voters between July 31 and Aug.2. It is considered accurate to within 3.5 per cent, 19 times out of 20.