The Ontario government should drop the eight per cent harmonized sales tax on hydro bills, provincial NDP Leader Andrea Horwath proposed Monday.

"People are being jolted every time they open their hydro bills," she said in a news release. "Taking the eight per cent HST off hydro bills would make life a little more affordable and give Ontarians a needed break."

Families with two or more children would save $135 a year, she said, and more than 5.9 million Ontario families would benefit from the plan.

Thousands of people have contacted the NDP about electricity bills they can't afford, she said.

"When a single mom says she has to choose between paying the hydro bill and putting food on the table, something has to change," Horwath said.

The NDP has launched website with an online petition asking the provincial legislature to remove the HST from electricity bills.

It's the party's second hydro-related announcement in four days.

On Thursday, the party said it had discovered that the provincial regulator, the Ontario Energy Board, had approved a hike in the guaranteed profits for Ontario electricity utilities.

Energy bills have risen steeply in Ontario since May, when an OEB-approved rate increase added about 10 per cent to the cost of electricity two months before the advent of the HST pushed it up another eight per cent.