One recent proposal from the Iranian side would involve a 10-year pause on enrichment, followed by another decade where Iran would agree to only enrich to levels well below weapons grade, according to a person familiar with the discussions. Meanwhile, Trump has told reporters that he wants no enrichment indefinitely and is against even the 20-year pause.

The Trump administration is also considering unfreezing $20 billion in Iranian assets as part of ongoing negotiations with Tehran, CNN previously reported. The step would come in exchange for Iran turning over its stockpile of highly enriched uranium.

How flexible each side is on their terms will ultimately dictate whether a deal can be reached.