Vegas casino magnate and big-time Republican donor Sheldon Adelson is set to endorse Marco Rubio, according to sources cited by Politico.

Rubio, currently running third in the Real Clear Politics polling average, is seeking out support from the mega-donors like Adelson that can help keep a campaign going for the long haul.

Last week, during a campaign swing through Las Vegas, Rubio held a meeting in Adelson's offices at the Venetian Las Vegas, one of a number of five-star luxury casinos the billionaire mogul owns around the world. Adelson, seated at the head of his conference table, heaped praise on Rubio’s performance while he discussed the dynamics of the 2016 race. Those briefed on the meeting described it as short but said it had an air of importance, with the two joined by Rubio’s campaign manager, Terry Sullivan, and a pair of senior Adelson advisers, Rob Goldstein and Patrick Dumont.

Politico cites unnamed sources as saying while Adelson has not firmed up his support he is leaning towards Rubio and an endorsement could come by the end of the month. In 2012 Adelson spent a reported $100 million on Republican candidates during the 2012 election cycle.