An anti-HST petition canvasser, right, gathers another signature in Vancouver. (CBC)

B.C.'s anti-harmonized sales tax petition has now signed up at least 15 per cent of registered voters in all 85 ridings in the province, organizers say.

Elections BC requires that 10 per cent of voters sign the petition before it is officially accepted, but the Fight HST campaign had set a threshold of 15 per cent to help ensure the effort would succeed.

"This means that one of every three signatures would have to be discarded in any one of our ridings for the petition to fail," said head organizer Chris Delaney.

'It is time for Premier Campbell to wake up and smell the coffee'—Fight-HST leader Bill Vander Zalm

Delaney said 653,240 people had signed the petition as of Sunday night, meaning that more than 40 per cent of voters who cast a ballot in the last election had added their names to the anti-HST effort.

In a number of ridings held by the Liberal government, more people have signed the petition than voted for the Liberal MLA in the May 2009 election.

Kill the HST now: Vander Zalm

Fight HST leader and former B.C. premier Bill Vander Zalm said he believes current Premier Gordon Campbell should kill the HST now.

"It is time for Premier Campbell to wake up and smell the coffee and get rid of this tax," Vander Zalm said in a release. "Stop fighting your own people and cancel the HST now."

The HST — which comes into effect July 1 — combines the five per cent federal GST with B.C.'s seven per cent provincial sales tax for a 12 per cent levy on most goods and services in the province, including many that previously were subject only to the GST.

The anti-HST petition campaign must submit its collected signatures to Elections BC by July 5 for verification.

The B.C. government would have a few options in response to a verified petition, including holding a non-binding referendum or introducing a bill in the legislature repealing the HST.

Campbell's government currently has a 13-seat majority, down from 14 following the resignation of Energy Minister Blair Lekstrom from the cabinet and the Liberal caucus last week.

Lekstrom said he quit as a personal protest against the way the government is handling the HST issue.

Economists endorse HST

Despite the public sentiment in B.C., some of Canada's top economists are encouraging people there and in Ontario to support the HST.

The Canadian Press has obtained a copy of an open letter signed by some of the country's best known private and public sector economists, saying they "strongly support implementation of the HST," because "it will promote investment, jobs and higher wages."

The letter, dated June 15, was signed by former Bank of Canada governor David Dodge and economists Don Drummond of TD Bank Financial Group, Warren Jestin of Scotiabank and Sherry Cooper of BMO Capital Markets, among others.

It said the HST will make the provinces more competitive by eliminating the retail sales tax currently hidden in the costs of goods purchased by businesses.

"This [retail sales] tax becomes embedded in the cost of goods at each stage of the production, distribution and retail processes," write the economists.

"The result is a compounding of the tax that is ultimately paid by consumers through higher prices."

With files from The Canadian Press