A scene from Hollywood Casino, which in 2010 became Maryland’s first open slots facility. (Photo by Doug Kapustin/For The Washington Post)

O’Malley (D) had been eying a Thursday announcement but ran into scheduling difficulties with Maryland House Speaker Michael E. Busch (D-Anne Arundel) and State Senate President Thomas V. Mike Miller Jr. (D-Calvert), both of whom the governor has asked to attend.

The session would mark the largest attempted expansion of Maryland’s gambling program since 2008, when voters approved five slots locations.

Legislation during the session is expected to include authorization of a Prince George's County casino and Las Vegas-style table games, such as blackjack and roulette, at existing gaming sites.