A release from Premier Kathleen Wynne's office says Couillard's visit "presents a significant opportunity to deepen the relationship" between Ontario and Quebec.
Wynne has asked Ontario's Progressive Conservative and NDP Leaders to support her invitation to have Couillard address the legislature May 11.
Wynne and Couillard have held four joint Ontario-Quebec cabinet meetings, and Quebec will host the fifth this fall.
The last Canadian premier to address the Ontario legislature was former Quebec premier Jean Lesage in 1964.
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