PHOENIX (AP) -- U.S. Sen. John McCain faced a tough crowd largely opposed to military action in Syria during a town hall meeting Thursday in Phoenix.
The Republican senator repeatedly told about 150 constituents at the morning meeting that there would be no plans to send U.S. troops.
"I want to begin by saying to you I am unalterably opposed to having a single American boot on the ground in Syria," McCain said. "The American people wouldn't stand for it.
"Second of all, it would not be anything but counterproductive to do that. American blood and treasure is too precious to do that."
While McCain had planned to talk about immigration and other issues at the gathering at a public library, Syria dominated the conversation. The senator was interrupted from the start by someone shouting that his response wasn't good enough.
A few held up signs from their seats with messages such as "Don't bomb Syria" and "Security thru peace."
McCain told the audience the American public soon would see irrefutable evidence that Syrian President Bashar Assad was behind a deadly chemical weapons attack.
"If we open the door to the use of chemical weapons and let it go unresponded to, then I think that sends a signal to other people that want to use them, that they can do so with impunity," McCain said.
The town hall meeting was one of two planned for Thursday, with the other taking place in Tucson. McCain also is holding a town hall Friday in Prescott.
The gatherings come as President Barack Obama is requesting speedy congressional backing of a military strike in Syria to retaliate for an alleged chemical weapons attack on Aug. 21.
The Obama administration blames Assad for the attack in a rebel-held suburb of the Syrian capital of Damascus. Obama says more than 1,400 civilians died, including at least 400 children. Other casualty estimates are lower, however, and the Syrian government denies responsibility, contending rebels fighting to topple the government are to blame.
Despite widespread condemnation from allies of the alleged sarin-gas attack, few countries are likely to join the U.S. in undertaking military action if Obama moves forward with a strike.