TORONTO -- The Ontario government is about to start facing co-ordinated opposition from two of the country's largest unions bent on stopping what they describe as Premier Doug Ford's "destructive agenda."

The heads of both Unifor and the Ontario Public Service Employees Union announced their alliance in the wake of Ford's reaction to General Motors' planned plant closure in Oshawa, Ont., saying the premier's comments indicate his priorities do not lie with everyday workers.

Ford said last week that there's nothing his government can do to convince the automaker to change course, adding the company's president had told him, "the ship has already left the dock."

The union leaders contend that Ford and his Progressive Conservative government are more focused on corporate interests than the concerns of frontline workers and vow the two unions, with a combined membership of about 470,000 people, will be fighting back.

OPSEU President Warren "Smokey" Thomas said a weakened private sector will limit any government's ability to collect taxes and fund public services, adding pushing back against Ford would benefit all Ontario residents.

"We understand that public services are the great equalizer in society," Thomas said in a telephone interview. "It's in both our best interests, for our members and for society, to work together and co-ordinate our efforts and see if we can't back Mr. Ford up in some of his policies and encourage him to reinvest in public services."

Thomas said the alliance, announced at Unifor's Ontario Regional Council meeting held over the weekend, was prompted largely by Ford's reaction to news that GM planned to shutter its Oshawa plant next year, taking at least 2,500 jobs with it.

Ford has said union leaders and politicians who talk about saving the Oshawa plant are selling "false hope," adding that his government would help the affected workers find new jobs.

Both Thomas and Unifor National President Jerry Dias said Ford's reaction wasn't good enough. Thomas also criticized the premier for giving $34.5 million to Maple Leaf Foods for the construction of a consolidated plant in London, Ont., despite the fact the company will be shedding 300 net jobs by closing three other facilities in the province.

In a statement announcing their collaboration, Dias said Ford has given the two unions even more reasons to push back against his agenda.

"Between cowering to corporate interests, a dangerous public sector hiring freeze, and punishing the provinces' most vulnerable workers, Doug Ford has clearly shown his playbook," Dias said in the statement. "It's one attack after another against working people and our families."

The premier's office did not immediately respond to request for comment.

Thomas said the two union leaders had joined forces before, swelling picket lines and mobilizing protests during health-care sector strikes in the Ontario communities of Owen Sound and Thunder Bay.

This time around, he said it made sense for the two groups to "co-ordinate efforts" by lobbying legislators and speaking up against government moves that the unions feel could jeopardize workers.

Thomas said the unions will also push to reinstate some labour-related measures introduced by the former Liberal regime that have been reversed by the Ford government, including a $15 minimum wage that was planned for next year and more lenient sick day policies.

Thomas said the unions will try to see those measures put back in place through individual bargaining efforts.

-- with files from Adam Burns