Ontario Premier Dalton McGuinty smiles as he answers questions after speaking at a water conference in Toronto on Tuesday March 22, 2011. (Frank Gunn/Canadian Press)

The Ontario government has voted to approve a bill that will ban transit strikes in Toronto.

MPPs at Queen's Park voted 68-9 in favour of the Toronto Transit Commission Labour Disputes Resolution Act on third reading Wednesday. Only NDP members voted against the bill, which will designate the TTC an essential service and thereby prohibit any potential job action by unionized workers.

Once it's rubber-stamped by Lieutenant-Governor David Onley, it becomes law.

The vote is a major victory for Toronto Mayor Rob Ford, who campaigned on a promise to have the transit agency declared an essential service. Ford required provincial assent in order to enact the change, and council voted on Dec. 16 to ask the province to move ahead with appropriate legislation.

Bob Kinnear, the leader of the Amalgamated Transit Union which represents TTC workers, slammed the vote and threatened that his union will "come out swinging."

"This is all about trying to save Liberal seats in Toronto in the next provincial election, everyone knows that," said Kinnear in a release. "[Premier Dalton] McGuinty is being a lapdog for a union-hating right-wing mayor because he is afraid of Ford's political clout, not because he cares about transit in Toronto."

When asked to explain his threat, Kinnear responded this way: "If this administration thinks that they can bully us around because our right to strike has been taken away from us, I'm just making it clear that that's not going to happen."

ATU's contract expires Thursday, and the union is currently in negotiations with the TTC on a new deal.

After Wednesday's vote, Ontario Labour Minister Charles Sousa said the legislation shows how vital the TTC is to Toronto's economy.

"This is not about Toronto city council, it's not the about union leadership," said Sousa. "This is about the million and a half riders who depend on the TTC. We value the very men and women of the TTC who are doing their job. This speaks to how vitally important their work is."

But NDP Leader Andrea Horwath said the legislation sets a bad precedent for future labour negotiations in the province.

"The best way to get an agreement is at the bargaining table," said Horwath. "It's a simple matter of fair process and one that gets the best results."