Mark down this weekend as one of the important early dates on the Republican primary calendar. No, it’s not Iowa or New Hampshire, not yet. But it’s a noteworthy day nonetheless: It’s the latest round in the Adelson primary.

And so Saturday will see at least three potential GOP presidential hopefuls—Texas Senator Ted Cruz, former Texas Governor Rick Perry, and Indiana Governor Mike Pence—descend on casino tycoon Sheldon Adelson’s Venetian hotel-resort in Las Vegas to address the annual spring meeting of the Republican Jewish Coalition, a hawkish pro-Israel group that Adelson, the GOP’s top mega donor in 2012, has historically bankrolled with millions of dollars in recent election seasons.

While Cruz, Perry, and Pence may not have the political sizzle of other White House hopefuls—especially Pence, after the disastrous couple of weeks he’s had—they all boast the kind of credentials on Israel that makes them potentially attractive candidates to Adelson and other wealthy RJC board members. And it’s clear that the RJC and its marquee donor Adelson have a strong magnetic pull for party heavyweights: Former President George W. Bush, 2012 GOP nominee Mitt Romney, House Speaker John Boehner and other congressional leaders are slated to attend parts of the three-day weekend gathering that begins Friday.

Bush, who is to be the featured speaker at a Saturday dinner gala, will be well compensated, receiving a fee of about $250,000, according to two GOP sources. (A spokesman for the RJC told The Daily Beast that they do not comment on these “issues.”)

Last year’s RJC meeting at Adelson’s Venetian drew potential candidates led by Jeb Bush, Scott Walker, Chris Christie, and John Kasich.

But these RJC bashes are only part of a longer and intense—though sometimes whimsical—Adelson primary wherein candidates court the multi-billionaire while he has an opportunity to size up their policy positions, qualifications, and characters. In recent months in Las Vegas and Washington, Adelson has had several one-on-one chats or attended small events with other GOP hopefuls seeking to win his heart, mind, and big checkbook.

In February, for instance, former UN ambassador John Bolton, who also is mulling a White House run, unveiled the Foundation for American Security and Freedom to promote hawkish national-security stances and make them a high priority in the 2016 elections. Conservative sources say that Adelson wrote a seven-figure check to fund the outfit.

Sarah Tinsley, the director of the Bolton foundation, declined to comment on whether Adelson had made a donation. Bolton, who spoke at last year’s RJC event and recently penned a New York Times op-ed calling for bombing key Iranian nuclear facilities, has been “aggressively raising money” in recent months and “fundraising is going extremely well,” Tinsley said. Bolton’s new group is aiming to raise more than $5 million, she added, and expects to start running digital ads and deploying other tools in the second or third quarter this year.

Ever since a 2010 Supreme Court ruling opened the floodgates for corporations, individuals, and unions to give unlimited sums to outside groups directly advocating for or against candidates, Adelson has emerged as the biggest GOP campaign donor. In 2012, as I reported previously, the casino baron and his Israeli-born wife, Miriam, ponied up almost $150 million for various super PACs and politically active nonprofits, including ones tied to Karl Rove and to Charles and David Koch.

Not long after, Adelson told a Wall Street Journal reporter that he was prepared to “double” his donations in 2016, a commitment that in good measure is driven by his ardent support for Israel and close political and personal bond with conservative Prime Minister Benjamin Netanyahu. Adelson as well has voiced vehement opposition to a Palestinian state and is considered a strong critic of the proposed nuclear deal with Iran.

Some former government officials have joined watchdog groups in decrying the growing influence of Adelson and other mega donors on the political landscape. “There’s no question that mega donors, individually and collectively, are undermining our democracy,” said Daniel Kurtzer, a former ambassador to Israel under President George W. Bush who is now a professor of Middle East Studies at Princeton. “There has been influence by people like Sheldon Adelson, who is on the public record as articulating very hard-line, right-wing positions on Israeli-Palestinian issues.” A spokesperson at Adelson’s Sands Corporation declined to respond to questions for this article.

Adelson is typically blunt about his views on Israeli security matters. The casino owner has called the Palestinians a “made-up nation... whose existence is to destroy Israel.” And Adelson drew criticism from at least one prominent Jewish leader for reportedly remarking last fall at a Washington, D.C., conference of the Israeli American Council that “I don’t think the Bible says anything about democracy… Israel isn’t going to be a democratic state... So what?” The council, whose growing mission includes advocacy for an estimated 800,000 Israeli Americans, received $22 million during two recent years from Adelson and his wife, according to The Jewish Daily Forward.

While wooing Adelson to tap his big checkbook has become a growing priority for Republican candidates eyeing White House runs, the 81-year-old casino baron, whose net worth Forbes puts at almost $30 billion, is holding his cards close to his vest. The CEO and chairman of the Las Vegas Sands, the world’s largest casino company, Adelson has signaled through a top aide that he won’t start supporting a candidate until early next year.

But the allure of Adelson’s seven- and eight-figure checks seems to have spurred some White House hopefuls to go the extra mile in adopting hard-line Israel stances that jibe with the casino magnate’s views. Exhibit A: Jeb Bush’s rapid response to a recent speech to the liberal Israel lobby J Street by former Secretary of State James Baker III, a prominent Bush foreign policy adviser.

When Baker criticized Netanyahu for not working harder to achieve peace in the Middle East, Bush rushed to write a staunchly pro-Likud op-ed for National Review—which attacked the Obama administration’s negotiating stance with Iran over a nuclear deal—apparently to defuse considerable dismay voiced by Adelson and other major Jewish donors.

To vent his displeasure over the Baker speech, Adelson, among others, reportedly spoke to Mel Sembler, a close friend and fellow RJC board member, who’s already raising big bucks for Bush’s pre-campaign committees, according to a GOP source close to the Bush operation.

“Everybody was upset about it [Baker’s talk],” said one RJC board member with ties to Adelson, adding that “Jeb did what he needed to do.” Other Adelson confidantes say Baker’s talk has inflicted more lasting damage on Bush with some Jewish conservative donors—including perhaps with the casino owner himself. “Many important donors I’ve spoken to who care about Israel are disenchanted with Jeb Bush because of Baker’s talk and his role as an adviser,” said Morton Klein, the president of the Zionist Organization of America, another hawkish group of which Adelson has been a principal underwriter.

Adelson’s fervent support for Netanyahu’s policies was palpable during the recent elections when the Israeli leader won a fourth term. In 2007 Adelson financed the launch of a free daily newspaper, Israel Hayom, that now boasts the largest circulation in the country (the paper reportedly hiked its print run by almost 70 percent before the elections). “Adelson’s paper is known very clearly as a major political platform for Netanyahu and his policies,” said Ed Djerejian, an ambassador to Israel under President Bill Clinton who previously held State Department posts under Presidents George H.W. Bush and Ronald Reagan. As Netanyahu was fighting for his political life, “Hayom reflected [his] focus on security and helped him get the word out,” added Djerejian, the founding director of Rice University’s Baker Institute for Public Policy.

The casino owner’s influence was on display last month in Washington when he jetted into the city to take a front-row gallery seat for Netanyahu’s speech to Congress. During Adelson’s stay in the nation’s capital, Cruz and a few other chosen senators who are mulling or have just announced White House runs—including Lindsey Graham of South Carolina, Marco Rubio of Florida, and Rand Paul of Kentucky—got private time with him or were at small events where he was a prominent figure.

While in Washington, Adelson also co-chaired a fundraising event for Graham’s political committee, which Graham is using to test the waters while he weighs jumping into the GOP race.

Graham is one of Congress’s most ardent backers of Israel, but he also recently endeared himself further to the casino owner by sponsoring a Senate bill to ban Internet gambling, a top priority for Adelson and one that he’s bankrolling by hiring a team of high-priced lobbyists and making big campaign donations. The Graham event had another twist when former Senator Norm Coleman of Minnesota made a fundraising pitch for a new conservative national-security advocacy group he co-founded with two other ex-senators (Indiana Democrat Evan Bayh and Georgia Republican Saxby Chambliss).

Dubbed the American Security Initiative, the group helped push for legislation that mandates congressional review of any nuclear deal with Iran, a shift that could create obstacles for the Obama administration. “A few people stepped forward to support the initiative at the Graham event,” Coleman said in an interview. “It was a very good place to make a presentation.” Days later the fledgling outfit mounted a $500,000 ad blitz on cable television.

Coleman, a close Adelson ally and an RJC board member, added that he “fully anticipates there will be further activities and ad buys.” A GOP source said Adelson is expected to help fund the new security group, but Coleman declined to comment. Coleman added that one of two older groups he chairs, which back House GOP candidates and have pulled in about $20 million from Adelson and his wife in the last two elections, according to public documents and GOP sources, might get involved this year in promoting tougher national-security stances.

As Adelson surveys the early 2016 field Cruz is one of a few candidates to have had private meetings with the casino owner since last fall and seems to be spurring some interest, despite his weak standing with many in the GOP establishment, say some Adelson allies. But other Adelson confidantes, who are closer to the mainstream wing of the GOP, say Adelson thinks Cruz is probably a long shot because of his Tea Party brand of conservatism.

Adelson, who seems far from settled on any candidate yet, has also gotten together in recent months with Walker and Rubio. Rubio boasts very strong hawkish Israel credentials and other foreign policy views that appeal to Adelson. Walker has a famously solid anti-union record that’s a plus with Adelson, whose casinos have long been non-union.

Adelson, whom a few GOP operatives deem mercurial at times, has indicated through aides that the bar for his financial support will be higher this time than in 2012, and that he badly wants to see the GOP win the White House. Still, the casino billionaire could be torn between his penchant for backing a candidate in the primaries very closely in sync with his hawkish views and one with the best shot at winning the nomination and the presidency.

In 2012, Adelson and his wife poured some $15 million into a super PAC that was largely responsible for sustaining a brief primary run by a longtime political ally, former House Speaker Newt Gingrich of Georgia, which helped delay Mitt Romney from winning the nomination. The Adelsons later chipped in $30 million to a super PAC supporting Romney, about whom the casino owner early on voiced skepticism.