The White House on Thursday discouraged Kurdish leaders from splitting away from Iraq, saying the country needs to remain unified to defeat Sunni extremists.
Iraq would be better able to confront the "existential threat" posed by Sunni terror groups by binding together to combat the rebels, the White House spokesman said.
"We think that's in the best interests of all the citizens of Iraq, but what's incumbent upon Iraq's political leaders is for them to come together to put aside sectarian divisions and focus on the best interests of the country," Earnest said.
"And we're hopeful that Kurdish leaders will play a similarly constructive role in making that happen in the same way that we're appealing to the national interests of Sunni and Shia leaders to do the same thing."
Massoud Barzani, the president of Iraq's autonomous Kurdish region, on Wednesday asked his parliament to begin drafting an independence referendum.
In an interview with the BBC, Barzani said it was "a question of months" before his government proceeded with the effort.
“I have said many times that independence is a natural right of the people of Kurdistan. All these developments [in Iraq] reaffirm that, and from now on we will not hide that the goal of Kurdistan is independence,” he said.
The Kurds have operated in relative autonomy since the 1990s, and in recent weeks grabbed control of the historically and strategically significant city of Kirkuk.
It’s unclear how Turkey, a U.S. ally, would respond to the referendum. Leaders there have long been wary of an independent Kurdish state, although they may see one forming outside of its own borders as a preferable alternative.
Earnest said there had been "a lot of dialogue between senior administration officials and political leaders in Iraq," including top Kurds, about the developing crisis.
"Our message to them in private is the same message that I've been delivering up here publicly, which is that we believe it's in the best interests of all the citizens of Iraq for that nation's political leaders to come together, to set aside sectarian divisions, to set aside their own political ambitions and focus on the best interests of Iraq," Earnest said.