Major GOP megadonor Sheldon Adelson just got some of his money back from Marco Rubio

Billionaire casino mogul Sheldon Adelson, one of the Republican Party's biggest megadonors, got some of his money back from the presidential campaign of Sen. Marco Rubio (R-Florida) last month.

The campaign's July filing with the Federal Election Commission shows Adelson, his wife Miriam, and their daughter, Shelley, all received refunds of $2,600 contributions they made before Rubio launched his White House bid.

Adelson's support - and the money that comes with it - would give a major boost to any of the GOP presidential candidates. The quest to earn his backing has become known as the "Adelson primary." Rubio has been dubbed the "clear front-runner" in the Adelson sweepstakes, but this refund indicates he doesn't have the megadonor's support sewn up just yet.

A spokesperson for Adelson declined to comment on this story.

Both Sheldon and Miriam Adelson gave $10,200 to the Rubio Victory Committee in January. This joint fundraising committee transfers money to Rubio's campaign account and leadership PAC. The Adelsons' donations were split between the leadership PAC and Rubio's campaign account, which at the time, was dedicated to his Senate bids.

Campaign-finance laws allow donors to give a maximum of $2,600 to a candidate for their primary and general election races. The refunds received by Sheldon and Miriam Adelson are the portions of their donations to Rubio that were earmarked for his Senate general election race.

After Rubio announced he was running for president and would not run for Senate re-election in April, he was allowed to transfer the funds in his Senate account into the war chest for his White House bid. However, since the general election for Rubio's Senate seat has not yet begun, donors like Adelson who gave him money for that race would have had to sign forms redesignating the funds for his presidential campaign.

The refunds are a sign Adelson is not yet willing to publicly commit to supporting Rubio's White House bid. Rubio's campaign did not respond to a request for comment on this story.