"Of course, it's a challenge when they finally figure out who won, who lost and they'll have to figure out how to put together broader coalitions," Hill said.
"While it will be a protracted period where there will be a lot of political horsetrading, we believe that they will be able to form a government and that in the meantime, there's a lot of support for this process," the ambassador said on "GMA."
Obama hailed the elections Sunday and congratulated Iraqi people on their courage.
"Today's voting makes it clear that the future of Iraq belongs to the people of Iraq," the president said.
He was mindful that the voting is the beginning and "not the end of the long, electoral and constitutional process. The ballots must be counted. Complaints must be heard," adding, "the level of security spoke of the growing capability of the Iraqi security forces."
Obama reiterated the United States' commitment to withdraw U.S. troops by 2011, saying, "by the end of next year, all U.S. troops will be out of Iraq."
ABC News' Vija Udenans contributed to this report.