What does Newt Gingrich have in common with a proposed downtown Miami casino?

Both are being backed by the same man: Las Vegas Sands CEO Sheldon Adelson.

Adelson and his wife’s $10 million injection into a political committee slamming Gingrich rival Mitt Romney have emerged as a major subplot in Florida’s GOP primary, thanks to the flurry of television ads funded by their money. Less noticed is Adelson’s direct tie to the biggest controversy facing the Sunshine State’s tourism industry at the moment.

Sands is helping lead the fight to expand Florida’s gambling laws to allow casino resorts in Miami and elsewhere across the state. Adelson hosted local leaders in an office suite overlooking a potential Sands Miami site on the land known as the Miami World Center, a cluster of parking lots and night clubs a short walk from the AmericanAirlines Arena.

“He likes to talk, mostly about him and the things he’s done... He never mentioned any political allegiances,’’ Miami Mayor Tomas Regalado said of Adelson. The two of them met in an office suite in downtown’s Everglades residential tower late last year, near where Sands hopes to build a roughly 1,500-room hotel and a convention center twice the size of the one in Miami Beach.

“He didn’t promise anything,’’ Regalado continued. “He just said, ‘I’m here to tell you who I am.”

Though Sands executives have spent years lobbying for a Miami casino, their efforts were overshadowed in recent months by the big media splash made by Genting. The Malaysian-based casino giant bought The Miami Herald’s headquarters in May and launched a full-on campaign to convince Florida to build what was described at the time as the world’s largest casino.

Privately, Sands has been lobbying just as aggressively, with Adelson’s persona looming large in the pitch. Andy Abboud, the head of Sands’ lobbying operation, refers to “my boss” frequently in describing why the Sands approach to business would work in Miami.

Sands touts its plan to lure conventions and trade shows to Miami, citing Adelson’s legenday success in that business. Adelson’s support of the bombastic former Speaker of the House has brought new attention to a billionaire known for blunt remarks and staunch support of Israel.

“I don’t take comments from anybody unless you’re rich,’’ a chuckling Adelson said in a Jan 2011 CNBC interview thatwas quoted in a recent profile of the Sands CEO. “If you’re so smart, why aren’t you rich?”

The Gingrich campaign did not respond to an interview request for this story, and a Sands spokesman said the company wouldn’t comment. Genting also declined an interview request.

The son of a cab driver, Adelson made his fortune organizing trade shows. He bought a Vegas convention center in 1989 to house his popular Comdex computer show, which once was held at the Miami Beach Convention Center before it became so large. Adelson sold Comdex for $860 million in 1995, then spent $1.5 billion building the Venetian hotel in Vegas. The Palazzo came next, followed by four Asian casino resorts now churning about $4 million in profits every day.

Forbes this year listed the 78-year-old as the eighth richest American, with a personal fortune worth about $22 billion.