Washington (CNN) Republican Sen. John McCain, who is battling brain cancer in his home state of Arizona, says in his new book that his current term is his last and, as a result, he feels he can open up about how he sees the current political climate.

"This is my last term. If I hadn't admitted that to myself before this summer, a stage 4 cancer diagnosis acts as ungentle persuasion," he wrote in his book, "The Restless Wave," according to the excerpt published on Apple News on Monday . "I'm freer than colleagues who will face the voters again. I can speak my mind without fearing the consequences much. And I can vote my conscience without worry."

Referring to President Donald Trump, McCain wrote, "He has declined to distinguish the actions of our government from the crimes of despotic ones. The appearance of toughness, or a reality show facsimile of toughness, seems to matter more than any of our values."

McCain said he wants to see the nation's politics "return to the purposes and practices that distinguish our history" and says, "you're damn right, I'm a champion of compromise."

"I would like to see us recover our sense that we are more alike than different," he wrote. "We are 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."

Read More