GAMBLING’S PROMISE in Maryland has been oversold so often that voters probably stopped noticing some time ago. Casinos, they were told, would rescue the dying racing industry; preserve horse farms and the open space they occupy; send a gusher of money to schools; and balance the state’s budget. Three years after Maryland voters authorized slots casinos, horse racing is still ailing, school funding remains tight and the state budget faces a structural deficit, as usual.

None of that stopped Gov. Martin O’Malley (D) from calling a special legislative session in Annapolis for next month, aimed at expanding Maryland’s gambling program to include table games at existing casinos plus a new casino in Prince George’s County.

And the governor added a new spin: In the course of a two-minute video, he referred a half-dozen times to the jobs an expansion would create as well as new revenue that would flow to schools.

This wellspring of employment, Mr. O’Malley said, would create 2,000 permanent new jobs. (That’s a pittance in the context of Maryland’s overall job force of about 3.1 million, but never mind.)

The governor is determined, as he has frequently said, to take gambling off the state’s political agenda — “to put this issue behind us,” as he said again Friday. That’s understandable, for gambling has become a stumbling block in Annapolis that threatens to make him look ineffectual as he plans a race for president in 2016.

With that in mind, he is trying to forge a deal that would satisfy an array of competing agendas. The issue has been forced in part by Prince George’s County Executive Rushern L. Baker III, a longtime opponent of gambling who now supports a big new casino at National Harbor, the splashy development on the banks of the Potomac. Mr. Baker, strapped for cash in Prince George’s, wants the local revenue from gambling; he also hopes to enhance National Harbor’s brand.

Mr. Baker has an apparent partner in the gaming company MGM Resort International, which badly wants to build a casino at National Harbor — so badly it dropped its insistence that the state cut taxes on gambling revenue.

A major casino in Prince George’s, whether at National Harbor or, less likely, at Rosecroft Raceway, could cut into profits — and, possibly, local proceeds — at the recently opened Maryland Live! casino in Anne Arundel County and a still-unbuilt facility in Baltimore city. Those casino owners are asking to be shielded against losses in the event a new facility comes to Prince George’s. How to do that — whether by cutting taxes on slots, authorizing table games, extending casino hours — is one question. Another is whether it is the state’s role to guarantee minimum profits at casinos indefinitely.

We long opposed casinos in Maryland as a lure to corruption and gambling addiction and a de facto tax on the poor and the lower-middle class. But Maryland voters, including nearly 60 percent of Prince Georgians, voted in 2008 to let the games (well, slots) begin.

Given that, as well as competition from neighboring states whose casinos already have table games, it was unrealistic to expect no future expansion in Maryland. While rushing an expansion of gambling would be unwise, Mr. O’Malley’s concern — that gambling has poisoned politics in Annapolis and should be addressed — is justified.