Now Playing: The legacy of John McCain

Now Playing: Defining moments in the life of John McCain

Now Playing: Arizona Senate candidates Joe Arpaio, Kelli Ward on why they’re running

Now Playing: ‘I’ve loved my life, all of it’: Sen. John McCain leaves final farewell

Now Playing: A visit to the ‘Hanoi Hilton’ where John McCain was a POW

Now Playing: President Donald Trump ignores repeated questions on John McCain

Now Playing: The Briefing Room: Trump announces new trade deal with Mexico

Now Playing: Trump ignores questions about John McCain

Now Playing: ‘I lived and died as a proud American,’ McCain wrote in final message

Now Playing: George W. Bush and Obama asked to speak at McCain memorial

Now Playing: Trump announces new trade deal with Mexico

Now Playing: Inside the White House

Now Playing: ‘Start Here’ podcast: Controversial Facebook post complicates Arizona Senate primary

Now Playing: Gov. Christie to Trump on Mueller investigation: ‘Just stop talking. Just stop.’

Now Playing: Petraeus: ‘No one had the backs’ of servicemembers ‘more than McCain did’

Now Playing: Pelosi on McCain: ‘With all of his strength and pride, he had a sense of humility’

Now Playing: Junior Arizona senator: McCain ‘put service… over and above self interest’

Now Playing: Sen. John McCain dies after long battle with brain cancer

Now Playing: Trump continues to lash out at Attorney General Sessions

Now Playing: Sen. McCain discontinues treatment after yearlong battle with brain cancer