WASHINGTON — President Obama’s nominee to be the next US commander in Afghanistan said Thursday the security situation in the war-torn country is deteriorating and assured senators he will do a thorough review of American troop levels needed to stabilize the nation.

Army Lieutenant General John W. ‘‘Mick’’ Nicholson Jr. told the Senate Armed Services Committee that he will have a better sense of conditions in Afghanistan within a few months if he is confirmed by the Senate.

As wartime commanders must often do, Nicholson walked a fine line during his confirmation hearing. He supported the Obama administration’s exit strategy, which critics have derided as politically driven, while also promising the senators his decisions will be grounded in sound military strategy.

Nicholson would succeed General John F. Campbell, who is expected to retire. There are about 9,800 US troops in Afghanistan.

Associated Press