The Ambassador Bridge has so much traffic a second span is needed. (CBC)

Michigan senators have put off voting on a proposal to build a new bridge between Detroit and Windsor until the fall, a setback for Michigan Governor Rick Snyder who wanted the project approved by July 1.

Former governor James Blanchard is also frustrated by the delay.  He said he's never seen a project that could do so much good take so long.

Blanchard said it's no secret that the owners of the Ambassador Bridge are trying to protect their monopoly, and their money is affecting the process.

"Legislators should be very wary about taking support from people who don't tell the truth about the issues, and then they end up looking like they've been corrupted by campaign contributions when maybe initially they were well-intentioned or naive or poorly informed," Blanchard said.

A Michigan politician who supports Detroit River International Crossing project (DRIC) said the votes just aren't there to pass the bill now.

A Michigan Senate committee had just started hearings last week on legislation to clear the way for the bridge to be built.

The Canadian government has offered to pay up to $550 million for Michigan's share of the bridge, because the only bridge between the cities, the Ambassador Bridge, has become overloaded with traffic.

Ontario Intergovernmental Affairs Minister Monique Smith said Tuesday she remains optimistic the publicly owned bridge will be built.

'We think that there is the political will developing to see it move forward," she said.