Saudi Arabia, Qatar and other Gulf countries are expected to sign an agreement on Tuesday toward ending a diplomatic crisis in the Gulf after 3.5 years.

The big picture: A Saudi-led coalition severed ties with Qatar in 2017 and closed their airspace and sea routes to Qatari planes and vessels, citing Qatar's alleged support for terror groups and relations with Iran. In recent weeks, Saudi Arabia and Qatar have been under pressure from the Trump administration to end the dispute.

• The U.S. maintains close ties with both Qatar and its rivals, but the Trump administration's past several attempts to reconcile the parties have been unsuccessful.
• Both Gulf countries see the signing of the agreement as a gesture to the Trump administration and part of their effort to “clean the table” to prepare for the incoming Biden administration.
• Jared Kushner mediated between the parties and traveled to Saudi Arabia to participate in the signing during this week's Gulf Cooperation Council (GCC) summit.

The latest: Ahead of the signing of the agreement, the Kuwaiti foreign minister announced Saudi Arabia and Qatar would open their land, air and sea borders starting on Monday night.

Driving the news: Kushner traveled to the GCC summit in Al Ula, Saudi Arabia, with White House envoy Avi Berkowitz and adviser Brian Hook, who helped negotiate the agreement.

• The summit will be the first time the Emir of Qatar Tamim Bin Hamad al-Thani will visit Saudi Arabia since the crisis erupted in 2017. The leaders of Saudi Arabia, Bahrain, the United Arab Emirates, Oman and Kuwait will also attend.
• The leaders are going to sign an agreement which includes three confidence building measures: Saudi Arabia, UAE and Bahrain will lift the air and sea blockade of Qatar; Qatar will withdraw all lawsuits against its three Gulf neighbors; and all parties will stop their media campaigns against each other.

Behind the scenes: The deal was reached in principle during Kushner’s last visit to Saudi Arabia and Qatar several weeks ago, where he met Saudi Crown Prince Mohammed Bin Salman and Qatari Emir Tamim. Kushner has close relationships with both leaders.

• U.S. officials say that after meeting the Saudi crown prince, Kushner travelled to Doha with Hook while leaving close aides Avi Berkowitz and Adam Boehler behind in Saudi Arabia. The two mediated talks between the Saudis and the Qataris over the phone in real-time until a draft deal was reached.
• In the last few weeks, final discussions were held with the Saudis and the Qataris to ensure both sides were committed to the understandings that were reached, the officials told me.
• The White House also lobbied the UAE, Bahrain and Egypt — all three of which have reservations about the agreement, as they view Qatar in a very negative light and do not believe the Qataris are sincere.
• The deal almost fell apart on Sunday when a last-minute miscommunication created new tensions between the Saudis and the Qataris, sources briefed on the matter told me.
• Kushner and his team were supposed to leave on Sunday afternoon but postponed their trip. A source told me Kushner and his team were forced to negotiate with the Saudis and the Qataris into the night on Sunday until a solution was found. They left Washington en route to Saudi Arabia early Monday morning.

What they're saying: A senior diplomat from one of the Gulf countries told me the agreement is a step in the right direction and includes some positive developments — but it does not mark the end of the Gulf rift.

• “Some of the issues were solved, but the root causes for the rift — bad personal relationships between the leaders and big policy differences on Iran, Turkey and the Muslim Brotherhood — are still there," the diplomat told me.

The bottom line: The agreement, which will be signed on Tuesday, would be a last-minute achievement for Kushner and the Trump administration before President-elect Joe Biden takes office on Jan. 20.