Saudi Arabia's King Abdullah will meet with President Barack Obama, as differences over Iran and Syria overshadow a decades-long Saudi-US alliance.
The meeting on Friday comes as Saudi Arabia has strong reservations about attempts by Washington and other major powers to negotiate a deal with Iran on its nuclear programme, and disappointment over Obama's 11th-hour decision last year not to take military action against the Syrian regime over chemical weapons attacks.
Saudi-US relations, dating back seven decades, are "tense due to Washington's stances" on the Middle East, especially Iran, said Saudi analyst Abdel Aziz al-Sagr, who heads the Gulf Research Centre.
Whatever differences [the US and Saudi Arabia] may have do not alter the fact that this is a very important and close partnership.
The recent rapprochement between Tehran and Washington "must not take place at the expense of relations with Riyadh", Sagr told AFP news agency.
The interim agreement curbs Iran's controversial nuclear activities in exchange for limited sanctions relief, and is aimed at buying time to negotiate a comprehensive accord.
Sagr said that "arming the Syrian opposition will top the agenda" during Obama's visit, his second since his election in 2008.
Analyst Khaled al-Dakhil spoke of "major differences" with Washington, adding that Obama will focus on easing "Saudi fears on Iran and on regional security".
US security and energy specialist professor Paul Sullivan said Obama meeting King Abdullah could "help clear the air on some misunderstandings".
"However, I would be quite surprised if there were any major policy changes during this visit. This is also partly a reassurance visit," he added.
White House spokesman Jay Carney has said that "whatever differences [the US and Saudi Arabia] may have do not alter the fact that this is a very important and close partnership".
However, Riyadh seems to be reaching out more towards Asia, including China, in an apparent bid to rebalance its international relations.
Crown Prince Salman bin Abdulaziz this month visited China, Pakistan, Japan, and India, to reportedly "strengthen ties".
Obama and the king are also expected to discuss deadlocked US-brokered Israeli-Palestinian peace talks.
They will also discuss Egypt, another bone of contention since the 2011 uprising which ousted Hosni Mubarak, a staunch US and Saudi ally.