Washington (CNN) It's July 2019 in Washington, and President Donald Trump is again attacking Paul Ryan, a feud that might have died with the former House speaker's retirement in January.

But the on-again, off-again duo is back in the spotlight thanks to new comments in a forthcoming book and Trump has found the time to punch back about Ryan's assertions the President doesn't understand government.

"American Carnage" by Politico's Tim Alberta depicts a Republican Party that at first struggled with Trump's rise during the campaign before gradually coming to terms with him as President, according to a report by The Washington Post , which obtained a copy of the book.

Alberta writes that Ryan left Congress in January because he couldn't bear the thought of another two years with Trump and saw retirement as an "escape hatch." In conversations with Alberta after retirement, Ryan, who had served nearly two decades in Congress, claimed Trump, a former real estate mogul, was ignorant about politics.

"I told myself I gotta have a relationship with this guy to help him get his mind right," Ryan says in the book, the Post reported. "Because, I'm telling you, he didn't know anything about government ... I wanted to scold him all the time."