WASHINGTON (Reuters) - The United States on Monday urged Iraq s federal government and Kurdish Regional Government institutions to resolve their disagreements after Iraqi Kurdish leader Masoud Barzani said he would resign later this week.  We call on all Kurdish parties to support the KRG as it works to resolve pending issues over the remainder of its term and prepare for elections in 2018,  U.S. State Department spokeswoman Heather Nauert said in a statement commending Barzani s decision. It urged Iraq and the KRG  to work urgently to resolve pending issues under the Iraqi constitution.  The statement appeared to reflect a U.S. belief that the departure of Barzani, whose Sept. 25 independence referendum is widely seen has having backfired, may make it easier for the two main Kurdish factions to work together and to negotiate with the federal government led by Prime Minister Haider al-Abadi. In the statement, Nauert stressed a U.S. desire to work with KRG Prime Minister Nechirvan Barzani, Masoud Barzani s nephew and a fellow member of the Kurdistan Democratic Party (KDP) faction, and with Deputy Prime Minister Qubad Talabani, a member of the other faction, the Patriotic Union of Kurdistan (PUK).  A strong KRG within a  unified and federal Iraq is essential to its long-term stability and to the enduring defeat of ISIS,  she said, referring to the Islamic State militant group, whose destruction is a major U.S. policy objective in the region.  Disputes between the KRG and the Baghdad federal government range from the perennial tussle over how to share oil revenues to the control of territory and border crossings. Suggesting that Barzani s departure may yield greater Kurdish unity and improve the odds of a resolution with Baghdad, a U.S. official said:  We can t allow this tension to continue. They have to be able to find a way to live together. Now is the time to get them to sit down and try to work things out.  