The White House believes it's getting close to an agreement with Iran on a one-page memorandum of understanding to end the war and set a framework for more detailed nuclear negotiations, according to two U.S. officials and two other sources briefed on the issue. The big picture: The U.S. expects Iranian responses on several key points in the next 48 hours. Nothing has been agreed yet, but the sources said this was the closest the parties had been to an agreement since the war began. Among other provisions, the deal would involve Iran committing to a moratorium on nuclear enrichment, the U.S. agreeing to lift its sanctions and release billions in frozen Iranian funds, and both sides lifting restrictions around transit through the Strait of Hormuz. Many of the terms laid out in the memo would be contingent on a final agreement being reached, leaving the possibility of renewed war or an extended limbo in which the hot war has stopped but nothing is truly resolved. Reality check: The White House believes the Iranian leadership is divided and it may be hard to forge consensus across the different factions. Some U.S. officials remain skeptical that even an initial deal will be reached. U.S. officials have expressed optimism about a deal at several points during previous rounds of negotiations and during the current war, but have yet to reach one. But the two U.S. officials said President Trump's decision to back off his newly announced operation in the Strait of Hormuz and avoid a collapse of the fragile ceasefire was based on progress in the talks. Behind the scenes: The one-page, 14-point memorandum of understanding (MOU) is being negotiated between Trump's envoys Steve Witkoff and Jared Kushner and several Iranian officials, both directly and through mediators. In its current form, the MOU would declare an end to the war in the region and the start of a 30-day period of negotiations on a detailed agreement to open the strait, limit Iran's nuclear program and lift U.S. sanctions. Those negotiations could happen in Islamabad or Geneva, two sources said. Iran's restrictions on shipping through the strait and the U.S. naval blockade would be gradually lifted during that 30-day period, according to a U.S. official. If the negotiations collapse, U.S. forces would be able to restore the blockade or resume military action, the U.S. official said. Zoom in: The duration of the moratorium on uranium enrichment is being actively negotiated, with three sources saying it would be at least 12 years and one putting 15 as a likely landing spot. Iran proposed a 5-year moratorium on enrichment and the U.S. demanded 20. The U.S. wants to insert a provision whereby any Iranian violation on enrichment would prolong the moratorium, the source said. Iran would be able to enrich to the low level of 3.67% after it expires. Iran would commit in the MOU to never seek a nuclear weapon or conduct weaponization-related activities. According to a U.S. official, the parties are discussing a clause whereby Iran would commit not to operate underground nuclear facilities. Iran would also commit to an enhanced inspections regime, including snap inspections by UN inspectors, according to the U.S. official. The U.S. would commit as part of the MOU to a gradual lifting of the sanctions imposed on Iran and the gradual release of billions of dollars in Iranian funds that are frozen around the world. The intrigue: Two sources with knowledge also claimed Iran would agree to remove its highly enriched uranium from the country, a key U.S. priority that Tehran has rejected up to now. One source said an option being discussed is moving the material to the U.S. What they're saying: Secretary of State Marco Rubio said Tuesday that "we don't have to have the actual agreement written in one day." "This is highly complex and technical. But we have to have a diplomatic solution that is very clear on the topics they are willing to negotiate on and the extent of the concessions they are willing to make at the front end in order to make it worthwhile," he added. But Rubio also called some of Iran's top leaders "insane in the brain" and said it was unclear whether they would make a deal.