The money keeps pouring into Maryland’s gambling campaign. MGM Resorts, the company angling to build a casino at National Harbor, has chipped in another $3 million, according to the latest disclosure report.

MGM Resorts has opened an office at National Harbor, where the company would like to build a casino.( Photo by Jeffrey MacMillan )

That’s still shy of the $21.6 million that Penn National Gaming has reported giving to a ballot-issue committee to fight the expansion plan in an ongoing ad war on television, radio and the Internet.

Question 7 on next month’s ballot would allow a new casino in Prince George’s County, as well as table games, such as black jack and roulette, at the state’s five existing slots sites.

All told, companies with a stake in the outcome have contributed more than $43 million to the two dueling ballot-issue committees. Both committees must detail their spending in a report due to the State Board of Elections on Friday.

The pro-expansion side also has received $1.3 million from the Peterson Cos., the developer of National Harbor; and $3.4 million from a group led by Caesars Entertainment. Caesars is building a casino in Baltimore and wants to offer table games.

The latest report also includes a $10,000 contribution from Bozzuto & Associates, which plans to break ground shortly on an apartment community at National Harbor.

So far, Penn is the only company funding the opponents.

Penn owns Rosecroft Raceway, a Prince George’s facility that would be eligible to bid for a casino license if the expansion plan passes. But Penn officials argue that the deck is stacked against them, because Prince George’s County Executive Rushern L. Baker III (D) and others have championed National Harbor as a better casino site.

Penn also owns a casino in Charles Town, W.Va., that analysts say would take a significant hit if another large-scale venue opens in Maryland. Proponents of the measure have accused Penn of acting to protect its interests in Charles Town.

The company also owns a smaller casino in northeastern Maryland which stands to benefit from table games if the ballot measure passes.