WASHINGTON -- The United States may remove Sudan from its list of state sponsors of terrorism as early as next July, U.S. officials said Sunday, provided the government in Khartoum meets an assortment of benchmarks.

Of primary concern is a Jan. 9 referendum in which southern Sudan will vote on whether to secede from the northern part of the country. The south is widely expected to vote for independence.

The U.S. is insisting that the referendum proceed as planned, and that the northern-based government respect the results, before it will consider removing Sudan's terrorist designation.

The referendum is part of the 2005 peace agreement that ended a 21-year civil war between Sudan's mostly Muslim north and predominantly animist and Christian south that killed nearly 2 million people. The agreement also set up a unity government in Khartoum and an autonomous government in the south to rule until the southern referendum.

The two sides have been struggling over several issues, including borders, voting rights and control of oil-rich Abyei, which straddles the north-south border. Residents of Abyei are scheduled to hold a separate referendum on Jan. 9 to choose whether the region will join Sudan's north or a possible new country in the south.

Salva Kiir, president of southern Sudan, has expressed concerns about a serious risk of violence during the referendum.

Sen. John Kerry, chairman of the Senate Foreign Relations Committee, met with Sudanese leaders over the weekend and presented the Obama administration's proposal to remove Sudan from the terrorist list. It comes on top of a September offer of a range of incentives, including possible restoration of full diplomatic relations between the U.S. and Sudan.T