Developer Milt Peterson stands at the site where he wants to build a high-end casino at National Harbor in Prince George’s County. (Astrid Riecken — For The Washington Post)

With MGM’s newly disclosed donation to a pro-gambling group, For Maryland Jobs and Schools, which became public Tuesday, the two sides are now close to parity in what has become a full-on television ad war.

At issue is a plan to 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. The plan will appear as Question 7 on the state’s November ballot.

Penn National Gaming, which opposes the expansion plan, has reported giving the most: $9.5 million.

But allies of MGM have also ponied up. The Peterson Cos., the developer of National Harbor, has contributed $400,000.

And a group that includes Caesars Entertainment, which has a license to build a Baltimore casino, has contributed $1.1 million. Though Caesars does not welcome additional competition from a Prince George’s facility, the company says it wants table games, as well as a lower tax rate that is also part of the plan.

The campaign is being coordinated by competing ballot-issue committees, set up to handle the donations of gambling companies and other interested parties.

The gambling-expansion plan would invite bids for a Prince George’s casino for a swath of the county that includes both National Harbor and Rosecroft Raceway, a harness track in Fort Washington owned by Penn National.

Penn has argued that the deck is stacked against them, however, because Prince George’s County Executive Rushern L. Baker III (D) has championed the National Harbor site, a 300-acre mini-city on the banks of the Potomac River.

The pro-expanded gambling group has accused Penn of acting to protect a large-scale casino the company owns in West Virginia, arguing business there could be threatened by another large-scale casino in Maryland. Penn has denied that as a rationale.

Penn also owns an existing Maryland venue, Hollywood Casino Perryville in Cecil County.