Winning the backing of the 81-year-old Adelson would give Rubio a serious boost in his quest for the 2016 Republican nomination. His campaign is predicated on the idea that he can appeal to a broad swath of primary voters and stay in the race long enough to outlast well-funded establishment favorites like former Florida Gov. Jeb Bush and Wisconsin Gov. Scott Walker. To do so, he’ll need the support of deep-pocketed contributors like Adelson, whose $32 billion net worth makes him the nation’s 12th-richest person, according to Forbes.

In 2012, Adelson’s financial support allowed former House Speaker Newt Gingrich to stay in the presidential race long after other donors gave up on him.

Adelson’s attraction to Rubio is in no small part centered on the Florida senator’s outspoken support for Israel, an issue near and dear to the billionaire’s heart. Rubio has reached out to Adelson more often than any other 2016 candidate, sources close to Adelson say, and has provided him with the most detailed plan for how he’d manage America’s foreign policy.