Sen. John McCain (R-Ariz.) said Thursday that President Obama would be impeached if he deployed U.S. troops in Syria.

"No one wants American boots on the ground. Nor will there be American boots on the ground, because there would be an impeachment of the president if they did that," McCain told Phoenix radio station KYFI on Thursday.

McCain voted in committee Wednesday for a resolution to approve the use of military force against the Syrian government. On Saturday, Obama asked Congress to approve a limited military strike against Syria for the alleged use of chemical weapons against its own people.

Testifying before the committee Tuesday, Secretary of State John Kerry briefly appeared unwilling to rule out the possibility of U.S. troops being deployed in Syria. But he later said, "there will not be American boots on the ground with respect to the civil war."

McCain faced stiff push-back from constituents opposed to a military strike at a town hall meeting Thursday. He defended the necessity of an attack in his interview with KYFI and challenged those who say the United States has not demonstrated through intelligence that Syria launched a deadly chemical attack against its own people.

"For any of our listeners who say, 'See, they still haven't proved it': There's proof, and you'll be seeing more of it," McCain said.