A sniffer dog is pictured in the stage bleachers during a security sweep before a campaign rally by U.S. President Barack Obama in Las Vegas

 
A sniffer dog is pictured in the stage bleachers during a security sweep before a campaign rally by U.S. President Barack Obama in Las Vegas
A sniffer dog is pictured in the stage bleachers during a security sweep before a campaign rally by U.S. President Barack Obama in Las Vegas, Nevada, November 1, 2012. REUTERS/Jason Reed