US Republican mega-donor and hard-line Zionist Sheldon Adelson will be contributing $45 million to help GOP presidential nominee Donald Trump get elected in November, a report says.

Adelson donated $20 million to Senate Leadership Fund, a GOP super-PAC which is linked to Senate Majority Leader Mitch McConnell, and will reveal the donation on Tuesday, CNN reported on Monday.

The CEO of the Las Vegas Sands casino group will also contribute a similar amount to Congressional Leadership Fund, a super PAC focused on the lower chamber.

He is also planning to donate at least $5 million to the Ricketts family’s political operation in a bid to assist Trump. The owners of the Chicago Cubs are also likely to contribute to help the Republican nominee.

In May, Adelson endorsed Trump and signaled that he would provide him financial support.

Adelson told Trump in a private meeting that he was willing to spend more than $100 million for his presidential campaign, The New York Times reported. During the meeting, Trump reportedly stressed that he was committed to the "security" of Israel.

It was then reported that Adelson decided to significantly scale back on his donations to the congressional Republicans to boost Trump’s chances of being elected.

In a Washington Post article published in May, Adelson “strongly encourage[d]” those still on the fence about the divisive billionaire to do likewise.”

The multi-billionaire wrote that Trump “exemplifies the American spirit of determination, commitment to cause and business stewardship.”

“You may not like Trump’s style or what he says on Twitter, but this country needs strong executive leadership more today than at almost any point in its history,” Adelson wrote.

Sheldon Adelson (left) and his wife Miriam Adelson are standing with Israeli PM Benjamin Netanyahu. (File photo)

Adelson was listed by Forbes in June 2015 as having a fortune of $28 billion, making him the 18th richest person in the world.

He is a major contributor to Republican Party candidates, which has resulted in his gaining significant influence within the party.

Adelson, a Zionist Jew, has said his most important issue when considering which candidates to support in US elections is “the safety of Israel.”