Sen. John McCain aired his distaste for "evil" Vladimir Putin and expressed qualms about President Donald Trump's handling of the Russian leader, in an excerpt of his new memoir that was published in the Wall Street Journal on Friday.
McCain's memoir, "The Restless Wave: Good Times, Just Causes, Great Fights and Other Appreciations," is expected to be released on May 22. Arizona's senior senator and the GOP's 2008 presidential nominee has been home battling brain cancer, a diagnosis he revealed last year.
In the book's excerpts published by The Journal, McCain minced no words. He blasted both Russia's president and his party's leader, with whom he's had a number of public disagreements. Much of the published comments focus on Russia's suspected meddling in the 2016 election, and Trump's reaction to the controversy.
"Vladimir Putin is an evil man, and he is intent on evil deeds, which include the destruction of the liberal world order that the United States has led and that has brought more stability, prosperity and freedom to humankind than has ever existed in history," McCain wrote. "He is exploiting the openness of our society and the increasingly acrimonious political divisions consuming us."
Putin has vigorously denied all allegations that Russian meddling was in any way linked to the Kremlin. However, in February a federal grand jury indicted 13 Russian nationals and three Russian entities for alleged illegal interference in the 2016 election.
"Putin's goal isn't to defeat a candidate or a party. He means to defeat the West," McCain wrote. "He meddled in one election, and he will do it again because it worked and because he has not been made to stop," McCain wrote.
While the senator said he was skeptical about Trump or his aides colluding with Russia, he felt an investigation was needed to dispel the possibility that a U.S. president could be vulnerable to extortion.
McCain said he wanted to make Putin pay a "steep" price for Russia's role in the 2016 election, and faulted Trump for his "naivete" and "general lack of seriousness about Putin's antagonism to U.S. interests and values."
The investigation by Special Counsel Robert Mueller has engulfed the Trump administration, and hangs over GOP efforts to preserve its Congressional majority in November. While the president has insisted repeatedly there was no collusion with Russia, McCain remained critical of Trump's handling of the situation.
"President Trump seems to vary from refusing to believe what Putin is doing to just not caring about it," McCain wrote in his book. "He needs to comprehend the nature of the threat Putin poses. He needs to understand Putin's nature, and ours," he added.
The White House did not immediately respond to CNBC's request for comment.