Sen. John McCain, R-Ariz., blasted Joint Chiefs of Staff Chairman Gen. Martin Dempsey on Wednesday for doing what he called "great damage" to the Middle East and world. 

"General Dempsey is the most disappointing chairman of the Joint Chiefs that I have seen, and I have seen many of them," McCain told Fox News' "America's Newsroom." "He has supported the plan to completely withdraw from Afghanistan. He's basically been the echo chamber for the president. And one of the reasons why we are in the situation that we're in in the world today… is because of his lack of either knowledge or candor about the situation in the Middle East, and it has done great damage."

"All I can say is that he only has eight more months."

The criticism came as Dempsey, Secretary of State John Kerry and Defense Secretary Ash Carter faced questions on Capitol Hill over crafting new war powers in the fight against Islamic State militants.

"I am afraid that you will hear very little from them in the way of a strategy to defeat ISIS," McCain said of the Senate hearing.

"All intelligence indicates that [ISIS's] ultimate goal is to strike the United States of America. They can't destroy us, but there's no doubt that they're a direct threat."