Michigan voters turned down the ballot question; 60 per cent voted against it.
But Mickey Blashfield, speaking on behalf of bridge owner Matty Moroun, said there are still some outstanding legal questions.
"The vote was that the people don't want to amend the constitution, that's very clear, but that's far from interpreting it as a ringing endorsement of the flawed bridge proposal," Blashfield said. "Does the governor [Rick Snyder] have the constitutional authority to do an interlocal agreement? Does the agreement stand on its own?"
The agreement signed by Ottawa and in Michigan in June has been described as an interlocal agreement, that allows two government agencies to come to an agreement and end goal.
The new bridge still needs several approvals on the American side of the border. It needs a coast guard permit and presidential permit before it can proceed.
The governor is optimistic that construction could still begin in as little as six months, he said Wednesday.
Some observers believe Moroun will now take his battle to court on both sides of the border.
"We can’t say what will happen. I will not speak about what Mr. Moroun will do in the future," Canada's Transport Minister Denis Lebel said Wednesday. "We’ll do this bridge, I’m sure of it."