Major League Baseball 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," baseball commissioner Rob Manfred said Monday during an all-star game town hall meeting.

"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 played in Montreal from 1969 until 2004, at which point the franchise was relocated to Washington, D.C. and the team became known as the Nationals.

The team's decline from the mid-1990s onward left the Expos unviable but renewed interest in bringing a team back to Montreal has grown in recent years. The Toronto Blue Jays have drawn impressive turnouts in the pre-season games played at Montreal's Olympic Stadium in the past two seasons.

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.