Rick Tyler, a longtime Gingrich aide and now a senior adviser for Winning Our Future, declined to comment on the latest contribution. But the prospects of the group’s getting another cash infusion from the Adelsons appeared in doubt as recently as Sunday night, when Mr. Tyler said he would like to spend $10 million in Florida to aid Mr. Gingrich but did not have the money to do so.
And early Monday, as Mr. Romney and his allies signaled the start of an aggressive anti-Gingrich effort in Florida, Winning Our Future placed only a small, short-term advertising buy: $392,000, relatively little in a state with large numbers of expensive media markets.
News of the contribution came in a Twitter message on Monday evening by Jon Ralston, a columnist for The Las Vegas Sun.
Dr. Adelson’s contribution was made after days of public and private pressure from allies of Mr. Romney, who hoped to stem the flow of money to Mr. Gingrich and viewed Mr. Adelson’s continued help as potentially devastating to Mr. Romney’s chances.
One of Mr. Romney’s chief backers, John H. Sununu, a former New Hampshire governor, referred to Mr. Adelson in a recent television interview as “not so bright” and suggested that he would face retribution from investors in his casino empire. “Does he think people don’t remember when you attack them and pay for the attacks in the primary? Especially when one of the parties receiving that attack is the same investment community that he likes to go to to finance his expansions?” he said.
Just how dependent Winning Our Future is on the Adelsons’ money is impossible to say. Federal Election Commission rules do not require Winning Our Future and other candidate-specific super PACs to publicly report donors until Jan. 31— the same day as Florida’s Republican primary.
Through Monday, the group had reported spending $3.9 million in the primaries, three-quarters of it on advertisements attacking Mr. Romney.
Restore Our Future, the super PAC supporting Mr. Romney and run by a trio of his former aides, has spent far more: about $11.1 million through Monday, including millions of dollars on ads in Iowa against Mr. Gingrich widely credited with crippling his campaign there. On Monday, the group booked several million dollars’ worth of additional advertising time in Florida.
It is unclear if the group has attracted contributions at the Adelsons’ level; through the end of June, when it filed a midyear disclosure report with the commission, the group’s largest donors had given checks of $1 million.
Jeremy W. Peters contributed reporting.