John McCain in book excerpt: 'I don't know how much longer I'll be here'

The Arizona Republican who was diagnosed with brain cancer last year has written a memoir, "The Restless Wave: Good Times, Just Causes, Great Fights, and Other Appreciations," that will be released later this month.

McCain suggests in the book that while he does not know how much time he has left, he believes his work is still unfinished.

"Maybe I'll have another five years, maybe with the advances in oncology they'll find new treatments for my cancer that will extend my life. Maybe I'll be gone before you hear this, my predicament is, well, rather unpredictable," McCain says in the audio recording published by NPR on Thursday.

The one-time Republican presidential nominee and Vietnam War veteran says in the excerpt that he is "prepared" for whatever happens "or at least I'm getting prepared." But, he adds, "I have some things I'd like to take care of first, some work that needs finishing and some people I need to see, and I want to talk to my fellow Americans a little more if I may."

In the excerpt that follows, McCain makes a call for civility and for Americans to set aside their differences in favor of mutual respect.

"I'd like to see us recover our sense that we are more alike than different," the senator says, suggesting that the American public too often loses sight of the ties that bind the country together. "We argue over little differences endlessly and exaggerate them into lasting breaches," he said.

Striking a tone similar to a point he repeatedly made on the Senate floor in Washington, McCain says, "whether we think each other right or wrong in our views on the issues of the day, we owe each other our respect."

"We're citizens of a republic made of shared ideals forged in a new world to replace the tribal enmities that tormented the old one. Even in times of political turmoil such as these, we share that awesome heritage and the responsibility to embrace it," he said.

McCain has been at home in Arizona since late last year recovering from side effects associated with his cancer treatment.