President Obama's nominee to become ambassador to Iraq withdrew on Monday in light of revelations of personal conduct that spurred questions about his fitness to serve.

Brett McGurk wrote the president and Secretary of State Hillary Clinton on Monday to notify them that he had withdrawn his name from consideration over the position. Conservatives had questioned McGurk's nomination after emails surfaced detailing an extramarital affair between McGurk and a reporter, whom he subsequently married.

"[A]fter much thought over the past week, and having discussed the issue with my wife ... I bvelieve it is in the best interests of the country, and of our life together, to withdraw my nomination and serve in another capacity," McGurk wrote.

Tommy Vietor, a spokesman for the National Security Council, said: "While we regret to see Brett withdraw his candidacy there is no doubt that he will be called on again to serve the country."

The withdrawal means that the president must nominate another ambassadorial candidate for the high-profile position in Iraq. The relationship between the U.S. and Iraq is at an especially important inflection point, given the transition to a post-war relationship between the two nations.

President Obama marked the coming end of the war in Iraq by welcoming home troops who have returned from the front lines on Thursday in North Carolina.

"As your Commander in Chief, and on behalf of a grateful nation, I'm proud to finally say these two words, and I know your families agree. Welcome home," the president said at Ft. Bragg, where he was joined by first lady Michelle Obama.

It wasn't a "Mission Accomplished" speech; the president acknowledged that there is more to be done in Iraq. But he was clear that the road ahead for Iraq would be governed by the Iraqis themselves.

"Iraq's not a perfect place. It has many challenges ahead. But we're leaving behind a sovereign, stable and self-reliant Iraq with a representative government that was elected by its people," he said.

The president's speech somberly recounted the challenges that the armed forces faced in Iraq, speaking of the battles in Karbala and Baghdad, "The grind of the insurgency," the surge and the process of handing over operations centers to the Iraqis.  He also honored those who were killed and wounded while serving in Iraq," Over 30,000 Americans have been wounded. And those are only the wounds that show. Nearly 4,500 Americans made the ultimate sacrifice, including 202 fallen heroes from here at Fort Bragg."

And the president spoke of the sacrifices of families. "Let us give a heartfelt round of applause for every military family that has carried that load over the last nine years. You too have the thanks of a grateful nation," he said. 

Steps the White House has taken to help veterans as they transition to civilian life were outlined as well as a bipartisan bill that was passed in Congress last month that gives companies tax credits for hiring veterans and wounded warriors. 

The president also promised that the legacy of the servicemen and women who served in Iraq would endure, "In the names of your fallen comrades etched on headstones at Arlington, and the quiet memorials across our country, in the whispered words of admiration as you march in parades, and in the freedom of our children and our grandchildren."

The last troops are expected to roll out of Iraq by the end of December.  While few military personnel will be left in the country, it is expected that about 16,000 government workers, contractors and third-party nationals will be left there to run the U.S. embassy and continue to train Iraqis.