On Tuesday, Sen. John McCain dropped his threat to block Gen. Martin Dempsey's nomination for a second term as chairman of the Joint Chiefs of Staff, The Associated Press reported.

McCain said he won't stop Dempsey's nomination because President Barack Obama has the right to choose the team around him.

But, the Arizona Republican senator still critiqued Dempsey's assessment of potential U.S. military intervention in Syria.

AP said the general described Syria's civil war as a scenario that would be close to impossible to intervene. McCain said, outlined in a letter Monday to Sen. Carl Levin, D-Mich., chairman of the Senate Armed Services Committee, such statement was "most disappointing."

Last Thursday, Dempsey had said that military intervention could make matters worse.

He also wrote that establishing a no-fly zone to protect Syrian rebels would require hundreds of U.S. aircraft at a cost as much as $1 billion per month, and it didn't assure a change in the violent momentum of Syria's civil war, AP reported.

Earlier this year, McCain made a secret trip to the Syrian border in Jordan, where he met Syrian refugees, who expressed anger about the U.S.'s lack of involvement in the civil war.

McCain leads a bipartisan congressional group pressuring to provide U.S. aid to civilians, and Syrian government rebels fighting to overthrow President Bashar al-Assad.