Penn National gaming owns Hollywood Casino at Charles Town Races, which analysts say could take a hit if another large casino opens in Maryland. (Photo by Ricky Carioti/The Washington Post) (Ricky Carioti/WASHINGTON POST)

Penn National Gaming has ponied up another $6 million for its fight against Maryland’s ballot measure on expanded gambling, bringing its total outlay on Question 7 to $41.5 million, according to disclosure reports made public Friday.

With the latest contributions from Penn and other interested parties, the total cost of Tuesday’s ballot measure is now closing in on an eye-popping $80 million.

Question 7 would allow a new Las Vegas-style casino in Prince George’s County, as well as table games, such as black jack and roulette, at Maryland’s five previously designated slots sites.

Penn’s properties include a casino in Charles Town, W.Va., that analysts say would take a financial hit if another large-scale venue opened in Maryland.

MGM Resorts, which is angling to build a casino at National Harbor, has contributed $29.5 million to the campaign to pass Question 7.

The Peterson Cos., the developer of National Harbor, has also kicked in $1.7 million to the same ballot-issue committee, and a group led by Caesars Entertainment has given $4.6 million. Caesars plans to open a casino in Baltimore in 2014 that would benefit from the legalization of table games.

Two smaller pro-expansion ballot-issue committees have also reported receiving recent contributions totaling $1.3 million. The Caesars group and Peterson have made donations to those groups as well.