Will John McCain Take on Donald Trump in New Book?

True to his reputation as a legislative "maverick," Senator John McCain's new book "holds nothing back" and will offer a "no-holds-barred" assessment of the current state of Washington, according to a statement from his publisher. While the publisher made no explicit mention of McCain taking on President Donald Trump, the book may be an ideal opportunity for the senator to offer his thoughts on his fellow Republican.

The 81-year-old's latest book, The Restless Wave, starts with McCain's unsuccessful 2008 presidential run and continues on to cover recent developments in American politics, publisher Simon & Schuster said in a press release. Written with veteran speechwriter and frequent McCain collaborator Mark Salter (who backed Hillary Clinton in the 2016 presidential election), the book is set for a late May release. The book deal was finalized in February 2017.

Although Simon and Schuster didn't list President Trump among the topics McCain covers in the book, his seventh, any assessment of Trump in its pages is sure to make headlines.

McCain hasn't ruled out another Senate run in 2021, but given his age and declining health, a campaign for a seventh term seems unlikely. Arizona's senior senator has been battling glioblastoma, a form of brain cancer, since July and has been recuperating in Arizona since December 17. His daughter Meghan McCain recently told an Arizona newspaper there is no timetable for her father's return to the Senate.

Given that McCain, a moderate, likely doesn't have to worry about winning over Trump-loyal GOP primary voters again, he may have the opportunity to be more candid than ever about the party and its president.

Trump and McCain have a famously contentious relationship: Then-candidate Trump said McCain, who spent nearly six years as a POW in a North Vietnamese prison camp, was "not a war hero" in 2015. Trump has also repeatedly publicly criticized McCain for his deciding vote last year against a Republican health care overhaul.

In turn, McCain has been more willing than most in his party to criticize the president.

In October, McCain delivered an impassioned speech in Philadelphia that targeted Trump without mentioning him by name.

"To fear the world we have organized and led for three-quarters of a century, to abandon the ideals we have advanced around the globe, to refuse the obligations of international leadership and our duty to remain 'the last best hope on Earth' for the sake of some half-baked, spurious nationalism cooked up by people who would rather find scapegoats than solve problems, is as unpatriotic as an attachment to any other tired dogma of the past that Americans consigned to the ash heap of history," McCain said.

More recently, McCain issued a statement criticizing Trump for congratulating Russian president Vladimir Putin on winning his fourth term earlier this month.

"An American president does not lead the Free World by congratulating dictators on winning sham elections," McCain said.

McCain doesn't seem to need the money from a book deal; he was estimated to be the eighth richest senator in 2016 with a net worth of $14.7 million, according to the Center for Responsive Politics.​