Maryland Gov. Martin O'Malley, left, and House Speaker Michael E. Busch, take their seats at the start of a bill signing ceremony at the State House in May 2. (Cliff Owen — Associated Press)

“This compromise will put us in a competitive position with surrounding states,” O’Malley said as he signed the bill at approximately 10:30 a.m.

The legislation, on which the General Assembly completed work shortly after midnight, gives voters the final say, in what is expected to be a hard-fought ballot measure campaign.

The bill represents Maryland’s largest gambling expansion since 2008, when voters authorized five slots sites. Since then, Delaware, West Virginia and Pennsylvania have all allowed table games, such as blackjack and roulette, at their casinos.

As O’Malley signed the bill, Prince George’s County Executive Rushern L. Baker III (D) and several labor leaders, who have lobbied for the construction jobs that would come with a new casino, stood behind him.

Before the ceremony, Baker told reporters that he continues to favor National Harbor as a casino site in Prince George’s.

View Photo Gallery: From the moment you walk into the soon-to-be-completed Maryland Live! casino, it’s clear that this is Vegas — or as Vegas as Maryland gets.

As written, the legislation would invite bids from a swath of the county that includes both National Harbor and Rosecroft Raceway.

“National Harbor is the best site on the East Coast,” Baker said. “It’s the one I’ll be pushing.”

O’Malley was also joined at the bill signing by House Speaker Michael E. Busch (D-Anne Arundel) and Senate Majority Leader Robert J. Garagiola (D-Montgomery), who stood in for Senate President Thomas V. Mike Miller Jr. (D-Calvert).

Busch told the audience that while he has never been a big proponent of gaming, he wanted to ensure voters will have “the best product” to weigh in November.

Maryland Governor Martin O’Malley (D) signs a bill expanding gambling. (WJLA)