– Few people have more power in President Donald Trump’s White House than Madeleine Westerhout, his executive assistant who controls access to the Oval Office, delivers the president’s marker-scribbled messages, sends orders to top military officials, prints e-mails and articles to show Trump, and seeks to keep a tight grip on his schedule.

But she was not always a supporter of the president. On election night, Westerhout, then a Republican National Committee aide, broke down crying, “inconsolable” over Trump winning the election.

“To the amusement of her RNC peers, she was later chosen as the president’s executive assistant and now sits just outside the Oval Office,” writes Tim Alberta in “American Carnage,” a copy of which was obtained by the Washington Post ahead of its scheduled release Tuesday.

The book is filled with vivid details and on-the-record quotes from prominent Republican officials and includes an interview with Trump, who gleefully takes credit for the GOP’s shift while standing over the Oval Office desk and waving a poll that shows his approval numbers as soaring from his State of the Union.

“The Republican Party was in big trouble. I brought the party back. The Republican Party is strong. The Republican Party is strong,” he says, before pausing, according to the book. “They’ve got to remain faithful. And loyal.”

The book details how many Republicans who once criticized Trump quickly changed their tune after his election, striking a devil’s bargain with a man Alberta describes in the book as behaving in a way that is dishonest, amoral, narcissistic and uninformed.

Westerhout now tells others she would do almost anything for Trump, and he calls her “my beautiful beauty.”

“These guys have all convinced themselves that to be successful and keep their jobs, they need to stand by Trump,” Rep. Justin Amash of Michigan, who recently left the GOP over his differences with Trump, said in an interview for the book. “But Trump won’t stand with them as soon as he doesn’t need them. He’s not loyal. They’re very loyal to Trump, but the second he thinks it’s to his advantage to throw someone under the bus, he’ll be happy to do it.”

Perhaps no one has had a more tortured relationship with the president than former House speaker Paul Ryan, R-Wis. — who went from wanting to abandon Trump after the release of the “Access Hollywood” tape to working to enact his agenda, all while doing his best to avoid commenting on Trump’s tweets and controversial statements.

Now out of office, Ryan is back to critiquing Trump in conversations with Alberta, who writes that the former speaker could not stand the idea of another two years with the president and saw retirement as the “escape hatch.”

“We’ve gotten so numbed by it all,” Ryan says. “We have a responsibility to try and rebuild. Don’t call a woman a ‘horse face.’ Don’t cheat on your wife. Don’t cheat on anything. Be a good person. Set a good example.”

Ryan says he sees the presidency getting worse, with Trump determined to govern and campaign on his terms, rejecting calls from other Republicans to moderate his message in 2020.

“Those of us around him really helped to stop him from making bad decisions. All the time,” Ryan says. “We helped him make much better decisions, which were contrary to kind of what his knee-jerk reaction was. Now I think he’s making some of these knee-jerk reactions.”