MIAMI — There are two major hurdles standing in the way of Major League Baseball possibly returning to Montreal: Oakland and Tampa Bay.

Commissioner Rob Manfred spoke with media on Monday during an All-Star Game town hall meeting where he said MLB will continue to delay any plans for expansion until after the Oakland Athletics and Tampa Bay Rays get new ballparks.

"I think it would be difficult to convince the owners to go forward with an expansion until those situations are resolved," said Manfred.

"Once they're done, I think we have some great candidates," Manfred said. "I know the mayor of Montreal has been very vocal about bringing baseball back to Montreal. It was not great when the Expos left. The fact of the matter was baseball was successful in Montreal for a very long time. Charlotte is a possibility. And I would like to think that Mexico City or some place in Mexico would be another possibility."

The Expos split time between Montreal and San Juan, Puerto Rico, in 2003 and 2004 before relocating to Washington, D.C., and being renamed the Nationals in 2005.

Montreal mayor Denis Coderre has long lobbied for a return of professional baseball to the city.

The Athletics currently share the Oakland–Alameda County Coliseum with the NFL's Raiders. It was opened in 1966 and is considered antiquated.

Tropicana Field, where the Rays play, was opened in 1990. It is the smallest MLB stadium by seating capacity when obstructed-view rows in the uppermost sections are covered with tarp as they are for most Rays games.