Retailer Gerry Harvey says he is not stepping down from the campaign to have a GST placed on overseas online purchases.

Newspaper reports suggested he was retreating from the tax fight because of the criticism and personal attacks he has attracted from consumers.

Mr Harvey says that is not the case and he is 100 per cent behind the campaign and will remain so.

He says he would like to see other retailers take more of a public role, but he will never back down.

"That's not in my nature to run away - I'll stand up and fight," he said.

"If I think something is right I'll fight for it, always have. If it's wrong or I've been proved wrong I'll walk away and I'll apologise."

Mr Harvey is one of many retailers calling for the $1,000 tax-free threshold to be scrapped.

He says he is upset about the number of vicious attacks he has received as the unofficial spokesman for the Retail Coalition group.

He says he now wants a lower profile, but is not stepping away from the campaign.

"I'm un-Australian ... I'm a horrible person all because I just think it is wrong that overseas retailing has a free kick over the Australian retailer," he said.

"That's all I said and [now] I'm all these things."

Retail giants Myer, David Jones and Target also want the threshold removed, saying the Government has a responsibility to keep profits and jobs in Australia.

They argue the threshold gives overseas businesses an unfair advantage and say jobs will move offshore.

But Assistant Treasurer Bill Shorten yesterday said the Government would not be bullied by the big retailers.

"Some of the big retailers live in a world where they think that if they pick up the phone to a government minister, then the next day there will be a tax put on implementing their wishes," he said.

He said the Government would struggle to find enough customs officers to police GST on goods purchased online from overseas websites.

The Productivity Commission is now examining the structure of the retail industry, including the $1,000 tax-free threshold.