McGuinty says he's confident ongoing talks with the federal government over Atomic Energy of Canada Ltd.'s bid will yield a better deal, but he hasn't set a firm deadline.
And while the project is more expensive than anticipated, McGuinty says Ontario has the information ahead of time and that means it will be able to better assess how to deal with possible costs overruns.
Ottawa, McGuinty adds, must take into account the future of Canada's domestic nuclear industry as it "sharpens its pencils" to try to help top bidder AECL come up with a more competitive deal.
His comments follow reports that AECL wanted $26 billion to build two new reactors in Darlington, east of Toronto a total that would wipe out the whole amount budgeted for nuclear expansion in the province.
Energy Minister George Smitherman announced plans to put its nuclear power plans on hold last month because the bid was billions away from the $6 billion the province had expected to pay.
Neither Smitherman nor McGuinty would reveal the amount of the bid from AECL, deemed the only compliant proposal out of three offers, citing confidentiality agreements.
Greenpeace analyst Shawn-Patrick Stensil says Prime Minister Stephen Harper must say no to what would amount to a $20-billion nuclear bailout.
He also blasted Ontario for failing to disclose the cost escalation.