And if that means light rail instead of Mayor Rob Ford's vision for more subways, then so be it.
This week, Ford and his allies lost a crucial transit battle when council instead voted to revive an above-ground, light-rail plan.
The mayor insisted the vote was meaningless because the province would still go ahead with his subway plan.
After Wednesday's vote, Ford posted a message on his Facebook page reiterating his pledge to bring a subway line to Toronto's east end.
"The residents of Scarborough, Toronto's fastest-growing region, deserve underground rapid transit — and I promised to deliver it to them. Today's vote does not change my promise," Ford wrote.
"Great cities, like Paris, London and New York were built around long-term transit visions 100 years ago. Subways in Scarborough represent that long-term vision for our great city."
But McGuinty says he has been clear with Ford that the mayor needs the support of council before any subway plan goes ahead.
"Just as I appreciate the clarity that has been introduced into this in terms of the direction the City of Toronto wants to pursue for public transit, I've also been very clear with the mayor from Day 1," he said.
"At the time the memorandum of understanding was entered into, there was a specific provision that he's got to seek the support of the council.
"When I spoke with him — he reached out to me just last Friday — I confirmed once again that I needed the approval of the council. Should he receive that, great, we're off to the races. Should he not receive that, I told him, should council decide they want to pursue another direction, that is something I feel obligated to consider."
Councillors voted for a plan to put light-rail lines on Eglinton Avenue and Finch Avenue West, and to study a subway extension on Sheppard Avenue. Ontario Transportation Minister Bob Chiarelli told reporters at Queen's Park the province is waiting for the results of that study.
"I want to be clear that the plan endorsed yesterday by council is still very much a work in progress," Chiarelli said.
"While council has in fact prioritized three LRT lines — the Scarborough LRT, the Finch West LRT, and the Eglinton Crosstown LRT — they have also deferred judgment on the Sheppard Avenue corridor."
Earlier, a small group of protesters interrupted the premier's lunchtime speech to the Canadian Club.
— With files from Maria Babbage in Toronto
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