MGM Resorts International has pulled narrowly ahead of rival Penn National in one measure of the spending orgy surrounding gambling expansion by allocating another $6.7 million to the effort to win approval of Question 7 on Maryland's Nov. 6 ballot.

MGM, the prospective owner of a new casino at National Harbor in Prince George's County, disclosed Wednesday that has put contributed $29.5 million to the ballot committee supporting the question. That narrowly edges Penn National's $29.1 million -- at least until Penn National's next disclosure.

Penn National owns a casino in Charles Town, W. Va., that could lose much of its revenue if the referendum is approved and a casino is built at National Harbor. It also owns Rosecroft Raceway, which it has warned it could shut down if nearby National Harbor gets a casino.

Up until Wednesday, Penn National had been maintaining a lead over several million dollars over MGM in Maryland's most expensive political contest ever. The ballot committees on both sides have cumulatively spent about $56 million of the money they've kicked into the effort.

The legislation voters are being asked to approve would permit a casino in Prince George's -- the state's sixth -- and allow table games such as poker and craps. Rosecroft could compete for the casino license, but Penn National contends the deck is stacked against it.

In addition to inescapable TV ads, Marylanders are now finding their mailboxes flooded with slickly produced campaign literature from both sides. Proponents argue that the expansion would brings money to Maryland schools that is now being lost to out-of-state casinos. Proponents warn that there are no guarantees the money will stay in education and contend the plan is a bad deal for Maryland.