Supporters of expanded gambling have accused Penn National Gaming of trying to protect its casino in Charles Town, W.Va. (Ricky Carioti — The Washington Post)

The latest contribution — another $3.5 million from Penn National Gaming — was disclosed on Friday, a day after another $3 million outlay was reported by MGM Resorts.

Penn is fighting the expansion plan known as Question 7, which would allow a new Prince George’s County casino, as well as Las Vegas-style table games at Maryland’s five other slots locations. MGM, which is angling to build a casino at National Harbor, supports the measure.

To date, Penn has disclosed spending $25.1 million, while MGM has reported $17.4 million in donations.

Several other companies have contributed to the pro-expansion side, including the Peterson Cos., the developer of National Harbor, which has given $1.3 million; and a group led by Caesars Entertainment, which has given $3.4 million.

Caesars is building a casino in Baltimore and wants to offer table games.

Penn 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, which the company denies.

The company has also expressed interest in building a casino at Rosecroft Raceway in Prince George’s but argued the deck would be stacked against it in a bidding process with MGM.