Sen. John McCain, R-Ariz., may not be a solid “yes” vote for President Obama in regards to military action in Syria.

McCain, speaking to NBC host Savannah Guthrie on Tuesday, said he could not support something that he was “afraid may be doomed to failure.”

On the other hand, McCain said, voting against Obama’s request for military action would be “catastrophic” and would do “horrendous damage to the credibility of the president of the United States.”

McCain said that any military action in Syria would have to “degrade” Bashar Assad’s ability to use chemical weapons, deliver weapons to the Free Syrian Army and change the momentum on the ground, otherwise such action would not be worth it to the U.S.

To do nothing, McCain said, would have “consequences throughout the world,” but only engaging in a limited capacity that doesn’t change anything would also be detrimental.

When asked whether he believed Congress would agree to engagement in Syria, McCain said, “I hope so but it's got to be a resolution that will achieve the goals that I just described and, if it doesn't, then obviously I can't support it.”