WASHINGTON, D.C.: Green Beret commander Henry Shelton is next up to run the gauntlet in hopes of emerging as the new chairman of the Joint Chiefs of Staff, having been recommended for the post by William Cohen. If confirmed, Shelton,55, would be the first Special Operations officer to serve as the country's military advisor supremo. The ground commander for the 1994 U.S. invasion of Haiti and the head of the Special Operations Command, Shelton is by all accounts a no-nonsense muti-service military man in a multitask world. Which fits the agenda that awaits him: smoothing the way into NATO for Poland, the Czech Republic and Hungary; ensuring that the 1998 Bosnia troop pullout deadline is met, and dealing with a Pentagon cantankerous about shrinking budgets and expanding peacekeeping missions. But the best part about Shelton, who served as assistant commander of the Army's 101st Airborne Division in the Persian Gulf War, is that he looks to be scandal-free. President Clinton is said to have accepted Cohen's choice; expect an official announcement tomorrow.