When Republican politicians want to make their first pilgrimage to the Holy Land, there’s but one person to call: Larry Mizel. That’s why he’s arranging Scott Walker’s first-ever trip to Israel next week.

The billionaire homebuilder and Republican Jewish Coalition board member isn’t in the same league of political kingmakers as casino magnate Sheldon Adelson: He’s given only $600,000 in political contributions since 1998 compared to the $100 million Adelson spent in 2012. But Mizel has become the minder of choice for GOP governors, senators and presidential aspirants traveling to Israel. He opens doors, arranges meetings with Prime Minister Benjamin Netanyahu and other members of Israel’s ruling class, and provides the kind of guidance that helps his party’s candidates avoid the gaffes that can befall politicians abroad.

“He has become a go-to person for Republicans looking to understand Israel and demonstrate their support for it,” said Ken Toltz, a longtime activist with The American Israel Public Affairs Committee who has worked closely with Mizel for decades. “For Larry, it’s about building relationships and giving elected officials or aspiring elected officials that powerful on-the-ground experience that connects them to Israel and to him,” Toltz said.

Mizel hasn’t committed to support the Wisconsin governor, he’s just opening doors for him on the five-day trip as Walker seeks to demonstrate more command of foreign policy issues and national security, the top issue for GOP primary voters according to a recent poll.

“He definitely likes him,” said one Colorado Republican close to Mizel. “But he won’t commit. He will build a relationship and friendship with all of them, but that doesn’t mean he’ll throw his resources behind any of them. That’s just how Larry is.”

Walker has been boning up on foreign policy after making several awkward statements that raised concerns about his fitness to lead at a time marked by global conflict. His gaffes — including a comment that “the most significant foreign policy decision” of his lifetime was when Ronald Reagan fired air traffic controllers, and another suggesting that his experience battling Wisconsin’s teachers unions had prepared him to take on the Islamic State group — have made Walker eager to demonstrate more command of foreign policy and national security, the top issue for primary voters according to a recent poll.

“Within our primary, foreign policy is pre-eminent and that’s probably not something a lot of our candidates planned on,” said John Weaver, a GOP consultant who has advised a number of presidential campaigns. “There are a number of tests you have to pass and this is a big one.”

Ben Carson, who launched his bid for the White House this week, learned the pitfalls of falling short on that test earlier this year. His own “fact-finding mission” to Israel seemed to do more harm than good after a magazine profile depicted him asking staffers incredibly mundane questions about Israel’s legislative body, the Knesset, which he seemed to know nothing about.

Walker, who currently leads many polls of the still unsettled Republican primary field, has yet to officially launch his campaign for the White House. AshLee Strong, a spokeswoman for Walker’s Our American Revival PAC, continues to describe the governor’s RJC-sponsored trip as a “listening tour” but offered few details.

Walker’s new foreign policy adviser, Mike Gallagher, an Iraq War veteran and former Senate Foreign Relations Committee staffer, will be accompanying him as he tours Israel.

“He’s got to build up his foreign policy experience and be able to talk about U.S.-Israel relations because it’s going to come up in the primary,” said Elliott Abrams of the Council on Foreign Relations, who plans to meet with Walker while he’s in Tel Aviv to give a previously scheduled speech.

Walker is wary of being outflanked on Israel issues by other hawkish primary rivals. Florida Sen. Marco Rubio, who sits on the Senate Foreign Relations Committee, appears to have an inside track for the backing of Paul Singer, a hedge fund billionaire and RJC member from New York — and possibly with Adelson himself. Sen. Lindsey Graham of South Carolina, another foreign policy hawk likely to enter the presidential race, has also carved out a lane on national security and defense matters.

Rubio visited Israel two years ago, and New Jersey Gov. Chris Christie took a similar trip in 2012. Graham touts his on-the-ground experience, not just in Israel but in the broader Middle East, especially visiting battle zones where the U.S. has been engaged.

“I’ve been to Afghanistan 23 times now,” Graham repeatedly told supporters last weekend in South Carolina.

With Jeb Bush and others raising unprecedented sums of money through super PACs that could push the primary fight well into April 2016, Walker is hoping that Jewish Republican donors who are skeptical about Bush can help him keep up.

“Hopefully, foreign policy discussions are not driven by a need to capture fundraising dollars,” Weaver said. “I’m skeptical about that, but hopefully that’s not the case.”

Scott McConnell, co-founder of The American Conservative magazine, was even more blunt.

“He’s doing it because the way the Republican primary is set up, this is the only foreign policy issue that seems to exist,” McConnell said. “The Adelson primary seems to be the only issue that matters.”

Yet support for Israel is also a threshold issue for many in the Republican base.

“This is a strong grass-roots view now,” Abrams said. “You go talk to people in Arkansas and places where there’s not much of a Jewish population and there’s tremendous support for Israel.”

Colorado Gov. John Hickenlooper, a Democrat who is close to Mizel and a number of GOP donors, went on a Mizel-led tour of Israel in 2013 and called it “the most remarkable seven-day trip of my life.”

That trip, as recounted by Hickenlooper, included trips to sites like Jerusalem’s Wailing Wall, the Golan Heights, Yad Vashem and Masada, and featured camel rides, meetings with Israeli Prime Minister Benjamin Netanyahu and a three-hour dinner with former Prime Minister Ehud Barak.