Rome ? President Bush is turning to former Missouri Sen. John Danforth to make the administration’s Iraq case in the United Nations, choosing a Republican who was a Senate ally of his father and has been a troubleshooter for both Democratic and Republican presidents.

If confirmed by the Senate, as seems virtually certain, Danforth will succeed the current U.N. ambassador, John Negroponte, who will be moving to Iraq as Bush’s ambassador to the new government there this summer.

Since 2001, Danforth has been Bush’s special envoy to war-torn Sudan, where he has tried to mediate a peace agreement. He served in the Senate for 18 years and was on Bush’s short list as a possible vice presidential choice in 2000.

The president made the announcement that he would nominate Danforth in a statement released while he was in Rome on a three-day European trip. The U.N.’s role in post-occupation Iraq will be a major topic in discussions with European leaders this weekend.

A lawyer with a practice in St. Louis, Danforth, 67, is a former attorney general of Missouri. An heir to the Ralston Purina fortune, he is also a licensed Episcopal priest and a graduate of Princeton University and Yale University’s law school.

Bush nominated Negroponte in April to be the ambassador to Iraq’s interim government, which is to gain sovereignty on June 30.

During the Clinton administration, he acted as special counsel appointed by then-Atty. Gen. Janet Reno. He conducted a 14-month inquiry into the deaths in 1993 of about 80 Branch Davidians in Waco, Texas. His investigation cleared the FBI of wrongdoing.