WASHINGTON, DC - APRIL 26: After answering questions from reporters, Sen. John McCain departs the U.S. Capitol for a briefing on North Korea at the White House April 26, 2017 in Washington, DC. Members of U.S. President Donald Trump's national security team held a briefing on North Korea at the White House for the entire U.S. Senate. (Photo by Win McNamee/Getty Images)
U.S. Military Holds Special Twilight Tattoo Performance In Honor Of John McCain
ARLINGTON, VA - NOVEMBER 14: U.S. Sen. John McCain (R-AZ) speaks after he was presented with the Outstanding Civilian Service Medal during a special Twilight Tattoo performance November 14, 2017 at Fort Myer in Arlington, Virginia. Sen. McCain was honored for over 63 years of dedicated service to the nation and the U.S. Navy. (Photo by Alex Wong/Getty Images)
Senate Holds Confirmation Hearing For Mike Esper To Be Secretary Of The Army
WASHINGTON, DC - NOVEMBER 02: Senate Armed Services Committee Chairman John McCain (R-AZ) (C) leads a confirmation hearing for the secretary of the U.S. Army in the Dirksen Senate Office Building on Capitol Hill November 2, 2017 in Washington, DC. The committee heard testimony from a number of officials for positions at the Pentagon, including undersecretary for personnel and readiness and undersecretary for intelligence. (Photo by Chip Somodevilla/Getty Images)
John McCain Honored With Liberty Medal For A Lifetime Of Service
PHILADELPHIA, PA - OCTOBER 16: Sen. John McCain (R-AZ) give a thumbs up before receiving the the 2017 Liberty Medal from former Vice President Joe Biden (left) at the National Constitution Center on October 16, 2017 in Philadelphia, Pennsylvania. (Photo by William Thomas Cain/Getty Images)
John McCain Honored With Liberty Medal For A Lifetime Of Service
PHILADELPHIA, PA - OCTOBER 16: Sen. John McCain (R-AZ) receives the the 2017 Liberty Medal from former Vice President Joe Biden at the National Constitution Center on October 16, 2017 in Philadelphia, Pennsylvania. (Photo by William Thomas Cain/Getty Images)
John McCain Honored With Liberty Medal For A Lifetime Of Service
PHILADELPHIA, PA - OCTOBER 16: Sen. John McCain (R-AZ) makes remarks after receiving the the 2017 Liberty Medal from former Vice President Joe Biden (not shown) at the National Constitution Center on October 16, 2017 in Philadelphia, Pennsylvania. (Photo by William Thomas Cain/Getty Images)
Senators McCain, Graham, Cassidy and Johnson Discuss Health Care Reform
WASHINGTON, DC - JULY 27: Sen. John McCain (R-AZ) (R) and Sen. Lindsey Graham (R-SC) hold a news conference to say they would not support a 'Skinny Repeal' of health care at the U.S. Capitol July 27, 2017 in Washington, DC. The Republican senators said they would not support any legislation to repeal and replace Obamacare unless it was guaranteed to go to conference with the House of Representatives. (Photo by Chip Somodevilla/Getty Images)
Donald Trump Is Sworn In As 45th President Of The United States
WASHINGTON, DC - JANUARY 20: (L-R) Sen. Elizabeth Warren (D-MA), Sen. Bernie Sanders (D-VT) and Sen. John McCain (R-AZ) pose or a photo around Sen. Cory Gardner (R-CO) as they arrive on the West Front of the U.S. Capitol on January 20, 2017 in Washington, DC. In today's inauguration ceremony Donald J. Trump becomes the 45th president of the United States. (Photo by Drew Angerer/Getty Images)
Sen. John McCain (R-AZ) Cast His Vote In The 2016 Presidential Election
PHOENIX, AZ - NOVEMBER 08: Sen. John McCain (R-AZ) and his wife Cindy exit the Mountain View Christian Church polling place after casting their vote on November 8, 2016 in Phoenix, Arizona. Throughout the country, millions of Americans are casting their votes today for either Hillary Clinton or Donald Trump to become the 45th president of the United States. (Photo by Ralph Freso/Getty Images)
John McCain Primary Election Night Party
PHOENIX - AUGUST 24: U.S. Sen. John McCain (R-AZ) speaks to a group of supporters at his victory party after winning Arizona's primary election August 24, 2010 in Phoenix, Arizona. McCain, seeking a 5th term as a U.S. Senator from Arizona, defeated challenger J.D. Hayworth in Tuesday's primary. (Photo by Eric Thayer/Getty Images)
Elton John AIDS Foundation and The ONE Campaign Host Reception on Global HIV/AIDS Funding
WASHINGTON, DC - MAY 05: Sen. John McCain (L) (R-AZ) and Sir Elton John, Founder, Elton John AIDS Foundation, pose for a photo before an Elton John AIDS Foundation and The ONE Campaign hosted reception on global HIV/AIDS funding at the U.S. Capitol Visitor Center on May 5, 2015 in Washington, DC. (Photo by Paul Morigi/Getty Images for EJAF)
Sen. McCain Meets With Secretary of Defense Nominee Hagel
WASHINGTON, DC - JANUARY 22: Sen. John McCain (R-AZ) heads to his Russell Senate Office Building office before meeting with former U.S. Senator Chuck Hagel on Capitol Hill January 22, 2013 in Washington, DC. Hagel, who cochaired McCain's 2000 presidential campaign, has been nominated by U.S. President Barack Obama to succeed Leon Panetta as Secretary of Defense. (Photo by Chip Somodevilla/Getty Images)
Clinton, Gates, Chu And Mullen Testify At Senate START Treaty Hearing
WASHINGTON - JUNE 17: Secretary of State Hillary Clinton (L) talks with Sen. John McCain (R-AZ) before the start of a Senate Armed Services Committee hearing on Capitol Hill June 17, 2010 in Washington, DC. The committee is hearing testimony on what they billed as the New Strategic Arms Reduction Treaty (START) and implications for national security programs. (Photo by Mark Wilson/Getty Images)
Sarah Palin Campaigns With Senator John McCain
TUCSON, AZ - MARCH 26: U.S. Sen. John McCain (R-AZ) and former Alaska Gov. Sarah Palin (L) attend a campaign rally at Pima County Fairgrounds on March 26, 2010 in Tucson, Arizona. Palin traveled to Arizona to stump for McCain, who is facing a primary challenge in his bid for a fifth term in the Senate. Today's event marked the first time the pair had campaigned together since their failed 2008 presidential run. (Photo by Darren Hauck/Getty Images)
John McCain Campaigns As Election Day Nears
WESTERVILLE, OH - OCTOBER 19: Republican presidential nominee Sen. John McCain (R-AZ) (R) and his daughter Meghan McCain hold a campaign rally at the Rike Center at Otterbein College October 19, 2008 in Westerville, Ohio. With 16 days left before the U.S. presidential election, John McCain will campaign in the swing-states of Ohio, Missouri and Pennsylvania over the next three days. (Photo by Chip Somodevilla/Getty Images)
John McCain Accepts The Republican Party Nomination
ST. PAUL, MN - SEPTEMBER 04: Republican U.S presidential nominee U.S. Sen. John McCain (R-AZ) (R) stands with Republican U.S vice-presidential nominee Alaska Gov. Sarah Palin on day four of the Republican National Convention (RNC) at the Xcel Energy Center September 4, 2008 in St. Paul, Minnesota. U.S. Sen. John McCain (R-AZ) accepted the GOP nomination for U.S. President Thursday night. (Photo by Ethan Miller/Getty Images)
Barack Obama John McCain
Democrat Barack Obama (L) and Republican John McCain embrace at the conclusion of their second presidential debate at Belmont University's Curb Event Center on October 7, 2008 in Nashville, Tennessee. AFP PHOTO PAUL J. RICHARDS (Photo by PAUL J. RICHARDS / AFP) (Photo credit should read PAUL J. RICHARDS/AFP/Getty Images)
Barack Obama John McCain
Democrat Barack Obama (R) and Republican John McCain greet each other at Hofstra University at the end of their third and final presidential debate on October 15, 2008 in Hempstead, New York. AFP PHOTO / PAUL J. RICHARDS (Photo by PAUL J. RICHARDS / AFP) (Photo credit should read PAUL J. RICHARDS/AFP/Getty Images)
George W. Bush John McCain
Republican presidential hopeful Senator John McCain poses with US President George W. Bush May 27, 2008 before Bush's departure from Phoenix Sky Harbor International Airport in Phoenix. Bush was leaving Phoenix after attending a fundraiser for McCain. AFP PHOTO/Mandel NGAN (Photo by MANDEL NGAN / AFP) (Photo credit should read MANDEL NGAN/AFP/Getty Images)
George W. Bush John McCain
Republican presidential candidate John McCain (L) shakes hands with US President George W. Bush after recieving his endorsement in the Rose Garden of the White House in Washington, DC, March 05, 2008. President Bush on Wednesday anointed one-time bitter rival John McCain as his preferred successor and heir to the vastly unpopular Iraq war and deepening economic fears. AFP PHOTO/Jim WATSON (Photo by JIM WATSON / AFP) (Photo credit should read JIM WATSON/AFP/Getty Images)
Former Republican presidential candidate US Senato
PORTLAND, UNITED STATES: Former Republican presidential candidate US Senator John McCain (R-AZ) waves to the crowd 11 August 2000 at The University of Portland in Oregon. McCain is campaigning for Republican nominee George W. Bush. (ELECTRONIC IMAGE) AFP PHOTO/Paul J. RICHARDS (Photo credit should read PAUL J. RICHARDS/AFP/Getty Images)
US President Bill Clinton (L) is warmly greeted by
WASHINGTON, : US President Bill Clinton (L) is warmly greeted by former presidential candidate Sen. John McCain (R-AZ) at the annual Radio/TV Correspondents Dinner 06 April, 2000 in Washington, DC. McCain dropped out of the Republican presidential race last month after Texas Gov. George W. Bush's strong showing in primary voting across the country. AFP PHOTO Mario TAMA (Photo credit should read MARIO TAMA/AFP/Getty Images)
US Arizona Senator and Republican presidential hop
SANTA CLARA, UNITED STATES: US Arizona Senator and Republican presidential hopeful John McCain reacts to cheers from the crowd after speaking in a rally at the Santa Clara University in Santa Clara, CA, 06 March 2000 on the eve of the multi-state SuperTuesday primaries. (ELECTRONIC IMAGE) AFP PHOTO/ROBERTO SCHMIDT (Photo credit should read ROBERTO SCHMIDT/AFP/Getty Images)
GOP presidential hopeful US Senator John McCain (R
CAMDEN, UNITED STATES: GOP presidential hopeful US Senator John McCain (R-AZ) smiles as his wife, Cindy (L), waves, during a barbecue on the front yard of a supporter's house in Camden, South Carolina 08 January 2000. (ELECTRONIC IMAGE) AFP PHOTO/Paul J. RICHARDS (Photo credit should read PAUL J. RICHARDS/AFP/Getty Images)
US President Bill Clinton (2nd-L) talks to Senator
WASHINGTON, DC - JULY 11: US President Bill Clinton (2nd-L) talks to Senator John McCain (2nd-R) after announcing that the US is establishing normal relations with communist Vietnam as Senator Bob Kerrey (L) D-NE Secretary of State Warren Christopher (C) and Defense Secretary William Perry (R) look on during ceremonies at the White House in Washington, DC 11 July. Clinton pledged that the US would continue to press for a full accounting of more than 2,200 servicemen still listed as missing in Vietnam and neighboring countries. AFP PHOTO (Photo credit should read JOYCE NALTCHAYAN/AFP/Getty Images)
U.S. Sen. John McCain, a former POW, looks 31 May
HANOI, VIET NAM: U.S. Sen. John McCain, a former POW, looks 31 May 1993 at a display of personal belongings of American POWs at the joint POW/MIA archives center in the Hanoi Army Museum. McCain is with U.S. Sen. John Kerry and a delegation on a two-day visit aimed at obtaining more access to archives dealing with the fate of missing U.S. servicemen. (Photo credit should read HOANG DINH NAM/AFP/Getty Images)
VIETNAM-POLITICS-PETERSON
Undated picture shows US Representative Pete Peterson (L), US Senators John McCain (R) and John Glenn (rear) leaving Hanoi's central prison. Once nicknamed the Hanoi Hilton, it is where McCain and Peterson were detained as POW's during the Vietnam War. / AFP / HOANG DINH NAM (Photo credit should read HOANG DINH NAM/AFP/Getty Images)
U S Air Force Brig Gen Russell G Ogan Foreground Points The Way
P368426 08: (File Photo) U.S. Air Force Brig. Gen. Russell G. Ogan, Foreground, Points The Way To Navy Lt. Cmdr. John Mccain To A Waiting C-141A Starlifter Cargo Transport Aircraft March 14, 1973 In Hanoi, North Vietnam. Senator Mccain Had Just Been Released From A North Vietnamese Prison Camp. (Photo By Usaf/Getty Images)
Senator John Mccain Is Pulled Out Of A Hanoi Lake By North Vietnamese Army
P368426 01: (File Photo) Senator John Mccain Is Pulled Out Of A Hanoi Lake By North Vietnamese Army Soldiers And Civilians October 26, 1967 In Hanoi, North Vietnam. Mccain's A-4E Skyhawk Was Shot Down By A Surface-To-Air Missile. Mccain Broke Both Arms And His Right Knee Upon Ejection And Lost Consciousness Until He Hit The Water. (Photo By Getty Images)
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Mug Shot Of Senator John Mccain As A P O W Taken By The North Vietnamese
P368426 05: (File Photo) A Mug Shot Of Senator John Mccain As A P.O.W. Taken By The North Vietnamese Sometime Between 1967-73 (Photo By Getty Images)
This file picture taken in 1967 shows US Navy Airf
HANOI, VIET NAM: This file picture taken in 1967 shows US Navy Airforce Major John McCain lying on a bed in a Hanoi hospital as he was being given medical care for his injuries. John McCain, a current US presidential hopeful, was captured in 1967 at a lake in Hanoi after his Navy warplane was downed by the Northern Vietnamese army during the Vietnam War. One of his rescuers said 24 February 2000, McCain was well treated after being pulled from the lake by villagers. McCain said that upon capture he was beaten by an angry mob and bayoneted in the groin. (B/W ONLY) AFP PHOTO (Photo credit should read AFP/Getty Images)