Al-Bashir is wanted by the International Criminal Court on charges of war crimes and genocide related to the conflict.
Washington is set to announce that it will "ease some US sanctions on trade and investment," one of the officials from the outgoing administration of President Barack Obama said Thursday.
"We are taking these actions in recognition of positive steps the government of Sudan has taken," the second official said.
However, the decision "doesn't affect (President Omar) al-Bashir's war crimes nor does it lift the state sponsor of terror" designation, which also includes Syria and Iran, the official added.
Washington in November extended sanctions against Sudan for a year, saying it could lift them at any time if the African country were to do more to tackle terror.
Sudan has been subject to a US trade embargo since 1997 for its alleged support for Islamist groups. Al-Qaeda leader Osama bin Laden was based in Khartoum from 1992 to 1996.
In recent years, the government's scorched earth tactics against ethnic minority rebels in Darfur have been cited as a reason not to lift the sanctions.
But relations have improved lately, with Secretary of State John Kerry meeting with his Sudanese counterpart twice, while the US envoy for Sudan and South Sudan, Donald Booth, visiting Khartoum several times.
That prompted speculation about possible sanctions relief.
Still, the Darfur conflict -- which has killed 300,000 people and displaced some 2.5 million since it began in 2003, according to the UN -- has continued to dog relations.
Al-Bashir is wanted by the International Criminal Court on charges of war crimes and genocide related to the conflict. He denies the charges.
Washington refused Bashir a visa to attend the UN General Assembly in 2015, citing the ICC arrest warrant.