Veterans stand alongside empty boxes serving as a symbolic delivery of signatures on a petition calling for Senator John McCain(R-AZ) and other Republican leaders to withdraw their endorsement of Republican presidential nominee Donald Trump on August 4, 2016 on Capitol Hill in Washington,DC. The event is organized by military veterans, MoveOn.org and Common Defense PAC,and the signatures were actually delivered on a USB thumb-drive. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

Empty boxes serving as a symbolic delivery of signatures on a petition calling for Senator John McCain(R-AZ) and other Republican leaders to withdraw their endorsement of Republican presidential nominee Donald Trump on August 4, 2016 on Capitol Hill in Washington,DC. The event is organized by military veterans, MoveOn.org and Common Defense PAC,and the signatures were actually delivered on a USB thumb-drive. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

Retired US Navy Nuclear Machinist Mate 2nd Class Jim Lyons (C), alongside fellow veterans, carries empty boxes serving as a symbolic delivery of signatures on a petition calling for Senator John McCain(R-AZ) and other Republican leaders to withdraw their endorsement of Republican presidential nominee Donald Trump on August 4, 2016 on Capitol Hill in Washington,DC. The event is organized by military veterans, MoveOn.org and Common Defense PAC,and the signatures were actually delivered on a USB thumb-drive. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

Retired US Navy Nuclear Machinist Mate 2nd Class Jim Lyons (C), alongside fellow veterans, carries empty boxes serving as a symbolic delivery of signatures on a petition calling for Senator John McCain(R-AZ) and other Republican leaders to withdraw their endorsement of Republican presidential nominee Donald Trump on August 4, 2016 on Capitol Hill in Washington,DC. The event is organized by military veterans, MoveOn.org and Common Defense PAC,and the signatures were actually delivered on a USB thumb-drive. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

Retired US Navy Nuclear Machinist Mate 2nd Class Jim Lyons (C), carries empty boxes serving as a symbolic delivery of signatures on a petition calling for Senator John McCain(R-AZ) and other Republican leaders to withdraw their endorsement of Republican presidential nominee Donald Trump on August 4, 2016 on Capitol Hill in Washington,DC. The event is organized by military veterans, MoveOn.org and Common Defense PAC,and the signatures were actually delivered on a USB thumb-drive. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

Retired US Navy Nuclear Machinist Mate 2nd Class Jim Lyons (R), retired US Marine Sergeant Alexander McCoy (2nd R), alongside fellow veterans, carries empty boxes serving as a symbolic delivery of signatures on a petition calling for Senator John McCain(R-AZ) and other Republican leaders to withdraw their endorsement of Republican presidential nominee Donald Trump on August 4, 2016 on Capitol Hill in Washington,DC. The event is organized by military veterans, MoveOn.org and Common Defense PAC,and the signatures were actually delivered on a USB thumb-drive. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

WASHINGTON, DC - AUGUST 04: Navy airman 1st Class Nate Terani, the first Muslim to be selected to serve in the U.S. Navy Presidential Honor Guard, joins with other former members of the U.S. military to request that Sen. John McCain (R-AZ) and other Republican leaders withdraw their endorsement of Republican presidential candidate Donald Trump following a press conference on Capitol Hill August 4, 2016 in Washington, DC. Trump has become embroiled in controversy since responding to the family of U.S. Army Capt. Humayun Khan who was killed while serving in the U.S. Army in Iraq in 2004. (Photo by Win McNamee/Getty Images)

WASHINGTON, DC - AUGUST 04: Marine sergeant Alexander McCoy joins with other former members of the U.S. military to request that Sen. John McCain (R-AZ) and other Republican leaders withdraw their endorsement of Republican presidential candidate Donald Trump following a press conference on Capitol Hill August 4, 2016 in Washington, DC. Trump has become embroiled in controversy since responding to the family of U.S. Army Capt. Humayun Khan who was killed while serving in the U.S. Army in Iraq in 2004. (Photo by Win McNamee/Getty Images)