Bill Shorten was to the point when he said that he would not make a promise he couldn't keep on dropping a tax on tampons. Courtesy: Sky

BILL Shorten has backflipped on Labor’s commitment to scrap the “Tampon Tax”, declaring the budget cannot afford it.

Labor had supported a push by former Treasurer Joe Hockey to lobby the states to ditch a GST on tampons and women’s sanitary products.

All state treasurers would have to agree for the tax to be dumped.

Mr Shorten, speaking at a People’s Forum in Brisbane, confirmed Labor would not look to scrap the tax which is worth more than $400 million to the budget over 10 years.

“We can’t afford that,’’ he said.

“I”m not going to make a promise I can’t keep.

“When you take a GST off a matter then that’s forgone revenue.”

Controversy has long raged over the tampon tax because women are forced to pay the GST on their products but condoms are GST free.

Mr Shorten spent an hour taking questions from undecided voters alone after Prime Minister Malcolm Turnbull refused to attend the third showdown of the campaign.

The Opposition Leader produced a strong and comfortable performance in the town hall style performance.

Mr Shorten said he was happy to throw himself at as many debates and public appearances as possible because he didn’t want to “be a small target and hope the other mob fall over.”

"I like the old Malcolm Turnbull more than the new Malcolm Turnbull" Shorten Bill Shorten pulled no punches saying that on climate change, Malcolm Turnbull has had to sell his soul to secure the leadership. Courtesy: Sky

Mr Shorten said Mr Turnbull had short changed Queensland by not attending the forum.

“I’m sorry that my opponent chose not to be here tonight,’’ he said.

“I think Queenslanders do deserve to hear both points of view.”

People’s Forums are Mr Shorten’s clear strength.

He overwhelmingly won the backing of the room in the first forum of the campaign in Windsor.

Mr Shorten has conducted more than 30 town hall meetings across the nation since he became Opposition Leader.

The Opposition Leader’s grassroots populist stances on healthcare and education are a clear winner within the working class who make up the majority of the crowd.

The millionaire Mr Turnbull struggled in the last town hall style format.

After 100 voters listened to Mr Shorten, 57 per cent of audience members said they were more likely to vote Labor, 16 per cent were less likely to vote Labor and 27 per cent were still undecided, Sky News reports.