David Alward said increasing the tax, which stands at 13 per cent, and imposing highway tolls are some of the suggestions being discussed as Finance Minister Blaine Higgs prepares to release a provincial budget in March.
"I've been clear for an HST (increase) or bringing tolls in, there would either have to be a mandate — which I don't have — or a referendum," Alward said.
"This is way too early to determine if and what types of revenues that we would feel would make most sense to be going forward with."
His comments come after Higgs said last week that the Progressive Conservative government won't be able to meet a promise to balance the provincial budget by next year.
The deficit for this year has been projected to hit $356 million, but Higgs said that's expected to get worse.
The province's Taxpayer Protection Act requires a referendum if the government wants to introduce a new tax, raise the HST or impose highway tolls.