If not Allen, who gets NATO?

The stunning revelation that the Pentagon is investigating volumes of e-mails between ISAF commander Gen. John Allen and Jill Kelley, a socialite in Tampa, throws into doubt whether Allen will become the Supreme Allied Commander Europe, a position he has been nominated for. And if he does not, it raises the question of who would go in his stead.

The bench isn’t all that deep for a job first held by Gen. Dwight Eisenhower and seen as a preeminent combatant command, typically given as payback for a hardship tour or a prize given to a known quantity.

The slate of three- and four-stars across the military are seen as either too junior or lacking in the kind of gravitas a job such as SACEUR requires. Gone are the Mike Mullens, Jim Joneses, Dave Petraeuses and Stan McChrystals who have the confidence and, at least within defense circles, the star power, to lead.

“We have a really talented military, but after these ten years, when it has come down to picking people, especially in a pinch, suddenly it seems that there aren’t any,” said one former defense official who wanted to remain anonymous given the current sensitivity over the scandal.

Allen, according to a defense official, says the 20,000 to 30,000 pages of e-mails between him and Jill Kelley, the Tampa socialite linked to the Petraeus scandal, reflect no wrongdoing on his part. And Pentagon officials tell Foreign Policy that Allen, who is married, says he did not have an affair with Kelley.

But the volume of e-mails was enough of a flag for Defense Secretary Leon Panetta that he approved a Defense Department Inspector General investigation on the matter. That puts Allen’s promotion from ISAF commander to Supreme Allied Commander on hold.  Although White House spokesman Jay Carney said Tuesday that President Obama “has faith in General Allen,” there is a good chance that his promotion to Europe may not weather this storm. The investigation alone may take its toll: Adm. James Stavridis, the current SACEUR, missed an opportunity to get the job he wanted, as Chief of Naval Operations, because of an Inspector General investigation over finances. He was just last week cleared of all the issues raised, but many believe the investigation squashed his chances of getting the job.

That leaves a gaping hole in the combatant command lineup and few people with the skills to fill it.

Gen. Carter Ham, who currently heads U.S. Africa Command, would be an obvious choice as someone who is widely-respected and has exhibited the kind of warrior-diplomatic savvy that job demands. And although he was long expected to retire, he has already served as head of the Army’s subordinate command in Europe. But the questions raised about what he did or did not do regarding Benghazi, while frivolous to many, probably means the White House would be unlikely to put his name forward.

Chief among other candidates could be Gen. John Kelly, who was confirmed for U.S. Southern Command and arrived there in recent weeks but who could be redirected. Kelly spent two years in Europe, more than a decade ago, working in Belgium as the special assistant to the Supreme Allied Commander, for both Gens. Wesley Clark and then Joseph Ralston. If the White House is looking for someone to go to Europe right away, Kelly could be an easy choice.

The Army, upset at what it sees as a disproportionate number of Marines in key jobs, from Kelly at Southern Command to Mattis at Centcom to Lt. Gen. Tom Waldhauser as Panetta’s senior military aide, may lobby to send Gen. Lloyd Austin, now the vice chief of staff of the Army and ostensibly headed to U.S. Central Command next year, to Europe instead. And although he is expected to retire at the end of the year, Army Lt. Gen. Mark Hertling could be a prime choice because he is one of the few three- or four-stars with recent European experience. He just finished his own tour as the commander of the Army’s subordinate command in Europe.

Other up-and-comers who are still considered strong varsity players but haven’t yet risen to the level of consideration for such jobs include the Air Force’s Lt. Gen. Paul Selva, an air strategist who just arrived at the Air Force’s Air Mobility Command, and Gen. Will Fraser, now at U.S. Transportation Command.

One other choice could be the new Air Force Chief of Staff, Gen. Mark Welsh, who served at U.S. Air Forces in Europe prior to getting the nod for the Air Force’s top job.