Brett McGurk testified before members of the Senate Foreign Relations Committee during a nomination hearing. He would replace U.S. Ambassador to Iraq James Jeffrey if confirmed.
McGurk's hearing came as the Iraqi political climate grows increasingly hostile. The country's president is wanted on terrorism charges by Iraqi Prime Minister Nouri al-Maliki, who faces criticism at home for his strong hand in Baghdad.
McGurk told lawmakers that it was "good news" that political issues were the dominant theme as opposed to national security. He said during his testimony, however, that he was "deeply concerned" about growing political divisions.
McGurk had worked with Maliki to negotiate the terms of Washington's relationship with Baghdad after U.S. forces left the country in December under the terms of a bilateral defense agreement.
Ahmad al-Mesaree, a lawmaker with the Sunni-backed Iraqiya slate, told Radio Free Iraq that McGurk's close ties with Maliki were cause for concern.
"His statements and political positions have not been neutral toward the political factions," he said.
Iraqiya leader Iyad Allawi lost to Maliki in the latest round of elections.
The Iraqi Embassy in Washington told the news service, however, that Baghdad had "no objection or reservation" to McGurk's nomination.
McGurk has never served in a diplomatic role for the U.S. government.