A view of National Harbor. (Linda Davidson — The Washington Post)

The company’s contributions were made in recent days to For Maryland Jobs and Schools, the ballot issue committee supporting passage of the plan, according to election filings.

The money is the start of what is expected to be a multi-million dollar campaign on both sides over a plan to allow a Las Vegas-style casino in Prince George’s County and table games at Maryland’s existing slots locations. The measure is part of a busy ballot this fall.

For Maryland Jobs and Schools has started airing radio ads statewide and will air TV ads this week, according to a representative.

The gambling plan, passed this month by the General Assembly, would invite bids for a Prince George’s facility from a swath of the county that includes both National Harbor, the 300-acre mini-city on the banks of the Potomac, and Rosecroft Raceway, the harness track in Fort Washington.

The developer of National Harbor announced in June that it had enlisted MGM to operate a casino at the site, pending legislative and voter approval.

Penn National Gaming, the owner of Rosecroft, has vowed to fight the ballot measure. The company contends that the deck is stacked against it, given that National Harbor has been championed as a location by Prince George’s County Executive Rushern L. Baker III (D).