The postings, with their populist tone, started appearing on Facebook and Twitter a few weeks ago. Their message was simple: If people in New Jersey can play poker online legally, New Yorkers should be able to as well.

Less obvious was who was behind the nascent campaign, called Let NY Play. The rallying cry, it turns out, emanated from the Las Vegas headquarters of one of the biggest casino operators in the world, MGM Resorts International.

MGM, which reported nearly $10 billion in sales and revenue last year, has no casino in New York and is not among the companies vying for one of the four casino licenses the state is preparing to grant. But MGM has made no secret of its ambition to be a big player in the expanding realm of online gambling.

The company has lobbied in Albany, where it supported legislation introduced this year to legalize online poker. The main sponsor of that proposal, State Senator John J. Bonacic, a Republican whose district includes the Catskills, said allowing people to play poker online could be a source of additional revenue for the state.