With President Obama’s first choice to be the next supreme allied commander of NATO expected to take his name out of consideration, a shortlist of generals and admirals to take his place is already circulating at the Pentagon.

NBC News and other outlets Thursday reported that Gen. John Allen is likely to withdraw his nomination to be supreme allied commander in Europe out of concern that emails he sent to Tampa socialite Jill Kelley would be made public in a confirmation process.

Pentagon spokesman Lt. Colonel Steven Warren said Thursday, “It’s my understanding that General Allen has not made a decision yet on this.” Other administration officials said Allen, who just finished his tour as commander of the allied mission in Afghanistan, will be speaking to President Obama on Friday to convey his final decision.

If Allen bows out of the process, the shortlist for generals and admirals to take over NATO forces centers around four names so far. These include Adm. William Gortney, the commander of the U.S. Fleet Forces Command; Vice Adm. Robert Harward, the current deputy commander of Central Command; Gen. Robert W. Cone, the commander of U.S. Army Training and Doctrine Command; and the commandant of the Marine Corps, James Amos.

Allen himself was the victim of bad luck as commander in Afghanistan. Not only did he have to command the war after Obama decided to accelerate the withdrawal of U.S. troops and pursue often elusive negotiations with the Taliban, but Allen also was briefly ensnared in the sex scandal that sank the career of former CIA director and four-star general David Petraeus. Last month the Pentagon cleared Allen of any wrongdoing in connection with his emails with Jill Kelley. The White House also proceeded with his nomination. On Wednesday, though, Secretary of Defense Leon Panetta spoke with Allen and told reporters he urged him to take his time to make a decision.

Michael O’Hanlon, a senior fellow at the Brookings Institution, a liberal think tank in Washington, D.C., says that if Allen withdraws his name, he thinks Amos would be a good fit for the top slot at NATO. “I am a big fan of General Amos, the Marine Corps commandant, now at the two-and-a-half-year mark in that job,” he says. “It’s a bit early to leave, but he’d be excellent at it and keep it in the Marine Corps family.” Allen is a Marine Corps general.