When the king of Jordan embarked on a trip to Washington recently even though it was uncertain whether he would be able meet with the new US president, it was a sign of the importance of the monarch's mission.

King Abdullah, who headed to the US capital three days afterDonald Trump's controversial travel ban went into effect, did eventually see the president - briefly and not at the White House, but during the National Prayer Breakfast held at a Washington hotel, an unusual setting for such a meeting.

Before seeing Trump, Abdullah had already held talks with such key administration figures as Vice President Mike Pence and Pentagon chief James Mattis, as well as congressional leaders.

The king's travels

With his impromptu visit, Abdullah managed not only to become the first Arab leader to meet President Trump: He also beat Israeli Prime Minister Benjamin Netanyahu, who will be hosted by Trump on Wednesday, to Washington.

Abdullah's primary motive for going to the United States was not necessarily to talk about the travel ban, although that issue was surely also broached. Instead, according to the reports by The New York Times and others, Abdullah warned the new administration against moving the US embassy in Israel to Jerusalem, a campaign pledge of Trump's, and against encouraging Israel's settlement expansion, which he believes could led to an upheaval in the Middle East, hurt prospects for a two-state solution, undermine the fight against extremists and threaten the stability of his own country, where many displaced Palestinians live.

Just hours after Abdullah met with Trump, the White House released a very cautiously worded statement saying that new or expanded settlements in the West Bank "may not be helpful" to achieving peace in the Middle East. What's more, last week Trump also appeared to soften his rhetoric on the US embassy when he told an Israeli newspaper that a move from Tel Aviv to Jerusalem is "not an easy decision" and that "we will see what happens."

Against this backdrop, what could previously have been anticipated as a smooth visit of kindred spirits who repeatedly expressed their affinity for each other during the campaign has become a more challenging endeavor.

"They both have to tread carefully," said Iwan Morgan, who heads the US studies program at University College London. "I think there will be a lot of schmoozing in public, but whether that converts into private agreement on key issues that concern Netanyahu remains to be seen."

Despite their political affinity, Netanyahu and Trump will be trying to size each other up on their first official visit, said James Davis, an American scholar of international security at the University of St. Gallen in Switzerland.

That's why Davis doesn't expect concrete deals or agreements to come out of this meeting - which could be problematic for Netanyahu, who had greatly welcomed Trump's election after an acrimonious relationship with his predecessor, Barack Obama. 

"Netanhayu has to deliver something to his hard-line coalition partners because his own grip on power seems to be tenuous in the last few months," Davis said.

Both leaders will need to use the visit to show their respective domestic constituencies that they are on the same page, but "for international political reasons, Trump has to be more balanced than he was during the campaign because he can't afford to alienate important Arab allies," Davis added.

To achieve that goal, Morgan said, Trump "will be advised not to make any overly strong statements or concessions to Netanyahu," while "Netanyahu cannot push Trump too hard for the very simple reason that Trump does not respond well to that on a personal level."

Invoking Iran

How can Trump and Netanyahu show that they are on the same page if moving the US embassy and the settlements are viewed as too contentious to discuss for fear that they might offend key Arab allies?

Look for a tough line vis-a-vis Iran as a unifying stance, the experts said, noting that this would also allow many Arab leaders who are concerned about Tehran to join in.

"If you need an issue on which to demonstrate that you are on the same page," Morgan said, "Iran is the one."