Penn National Gaming, the biggest contributor to Maryland’s campaign on expanded gambling, owns a casino in Charles Town, W.Va., shown here. (Ricky Carioti/The Washington Post)

With the latest $5 million contribution by Penn, total outlays by companies with a stake in the expansion plan, which will appear as Question 7 on the November ballot, is about $32 million.

The ballot measure, being fought over in TV ads, would allow a new casino in Prince George’s County, as well as Las Vegas-style table games at Maryland’s five previously authorized slots locations.

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.

A recent poll showed Marylanders nearly divided on Question 7.

MGM Resorts, the company angling to build a casino at National Harbor, is the leading contributor to a ballot issue committee fighting for passage of the plan. MGM has reported giving $11.4 million so far.

The developer of National Harbor has given $400,000, while a group led by Caesars Entertainment has contributed $2.3 million. Caesars is building a Harrah’s-brand casino in Baltimore.