"The right word is pause," Bentley said in an interview.
The Ontario Power Authority believes future electricity needs in the region can be met without the conversion, and says it would save $400 million by scrapping the project, added Bentley.
The minister wants to see a detailed plan from the electricity planning agency before making a final decision, which he expects to receive shortly.
"We've been proceeding on the basis the conversion would happen, that the conversion was necessary," said Bentley.
"If someone tells me I can save up to $400 million, they've got my attention. Now I've said show me. We're at the show me stage."
The Progressive Conservatives are convinced the plant's conversion to natural gas will not proceed, and predict the Liberals will use the savings to help pay for their decisions to cancel gas plants in Oakville and Mississauga at a cost of at least $230 million.
It's wrong to blame the OPA or Ontario Power Generation, which failed to reach an agreement with the OPA on a pricing scheme for the energy to be produced in Thunder Bay after the conversion to natural gas, said PC energy critic Vic Fedeli.
"Let's be clear, this is not a delay, this is a cancellation," he said.
"I think Mississauga and Oakville prove that no energy decision is made without the blessing of the Liberal government of Ontario."
The New Democrats also lashed out at the Liberals for their delays in the long-promised Thunder Bay project.
"The Liberals promised this conversion in two election campaigns, and already spent $13 million starting work they later stopped," said NDP house leader Gilles Bisson.
"Once again, the Liberals are playing politics with our power system and that's not fair to communities like Thunder Bay."
The Northwestern Ontario Municipal Association said it doesn't understand why the OPA doesn't immediately provide Bentley with the studies that support its proposal to scrap the conversion to natural gas and prove there would be huge savings.
"The $400 million savings that has now been thrown out, we're all sitting there going where'd that come from," said NOMA president Ron Nelson.
"The OPA is telling everybody that there is enough power, then they should be able to produce that data and give it to the minister today. What's the holdup?"
It says the conversion must go ahead or northern Ontario could find itself short of power after winter storms or if water levels fall too low, added Nelson.
Even though he wants proof of the OPA's claims, Bentley said there is no shortage of electricity right now in the Thunder Bay region, even after accounting for new developments coming on line such as mines around the Ring of Fire deposits.
"There's more than enough power right now in the northwest, and as you look into the future the only time when it's questionable is if there's really, really, really low water and some other things happen," he said.
Locals fear the expansion of the so-called east-west tie line, which the OPA says will double its capacity from 300 megawatts to 600, won't be completed until years after they stop burning coal to generate electricity in Thunder Bay, and say they could be left in the dark.
"What do we do in the meantime," asked Nelson.
"What if we have a drought and can't produce on our hydro dams?"
The Liberal government has promised to phase out all coal-fired generating stations by 2014.
Northerners are tired of seeing the Liberal government bow to the concerns of southern residents, said Fedeli.
"Anything that we need in the north they call a subsidy; anything they do in the south they call an investment," he said.
"There is a huge divide swelling between the north and the south, and this is another example."