In his new book, “Guilty As Sin” (Regnery), out Tuesday, Edward Klein claims officials in the Obama administration decided before the first witness was interviewed that Hillary Clinton would not face prosecution over the handling of classified email. An excerpt:

Bill Clinton’s private jet was cleared for takeoff and was taxiing toward the active runway at Phoenix Sky Harbor International Airport when a Secret Service agent informed him that Attorney General Loretta Lynch’s plane was coming in for a landing.

“Don’t take off!” Bill barked.

As his plane skidded to a halt and then headed back to its parking space, Bill grabbed a phone and called an old friend — one of his most trusted legal advisers.

It was June 27, 2016 — one year into the FBI investigation of Hillary Clinton’s emails.

“Bill said, ‘I want to bushwhack Loretta,’ ” the adviser recalled. “ ‘I’m going to board her plane. What do you think?’ And I said, ‘There’s no downside for you, but she’s going to take a pounding if she’s crazy enough to let you on her plane.’

“He knew it would be a huge embarrassment to Loretta when people found out that she had talked to the husband of a woman — the presumptive nominee of the Democratic Party — who was under criminal investigation by the FBI,” the adviser continued. “But he didn’t give a damn. He wanted to intimidate Loretta and discredit [FBI Director James] Comey’s investigation of Hillary’s emails, which was giving Hillary’s campaign agita.”

Bill hung up the phone and turned to a Secret Service agent.

“As soon as her plane lands,” he said, “get the attorney general on the phone and say the president would like to have a word with her.”

Once inside Lynch’s plane, Bill turned on the Clinton charm. He gave Lynch’s shoulder an affectionate squeeze and shook hands with her husband, Stephen Hargove.

“Bill said he could tell that Loretta knew from the get-go that she’d made a huge mistake,” his adviser said. “She was literally trembling, shaking with nervousness. Her husband tried to comfort her; he kept patting her hand and rubbing her back.

“Bill made small talk about golf and grandchildren and [former Attorney General] Janet Reno, and he kept at it for nearly a half-hour. It didn’t make any difference what they talked about; all he wanted to do was send a message to everyone at Justice and the FBI that Hillary had the full weight of the Clinton machine, the Democratic Party, and the White House behind her.

“It was clearly tortuous for Loretta. Bill told me later that he noticed there were beads of sweat on her upper lip.”

One week later, Barack Obama invited Hillary to fly with him to North Carolina for a campaign rally. He wouldn’t have let her use two of the greatest symbols of presidential power — Air Force One and the podium with the Seal of the President of the United States — if he thought there was even the slightest chance she was going to be indicted. But Attorney General Lynch had privately assured him that she wouldn’t let that happen, and that the fix was in.

Many members of the mainstream media thought that FBI Director Comey was hell-bent on indicting Hillary. They called him the Eliot Ness of his time — squeaky clean and untouchable.

But that was a complete misreading of Comey.

He was affable, had a good sense of humor, and might come across as a straight arrow, but he didn’t get to be director of the FBI by falling off the turnip truck. It took huge ambition and an instinct for political survival.

Comey knew that if he recommended an indictment of Hillary — something that was fiercely opposed by the president, the attorney general, the Democrats in Congress, and the mainstream media — he’d ignite a firestorm and go down in history as the man who traumatized the country’s political system. What’s more, if after all of that, Hillary was found not guilty by a jury, it would blacken Comey’s reputation for all time to come.

The day after Obama and Hillary flew to North Carolina, Comey held a televised press conference in the FBI auditorium. Dressed in a blue shirt and gold tie, which matched the colors of the FBI flag standing behind his lectern, Comey methodically laid out a bill of indictment against Hillary Clinton.

He said that Hillary and her top aides at the State Department — Huma Abedin, Cheryl Mills, and Jake Sullivan — had been “extremely careless in their handling of very sensitive, highly classified information.”

On and on he went, for a full 10 minutes, making an iron-clad case that Hillary was guilty of gross negligence in her handling of classified material, and that she had violated a federal statute that did not require evidence of intent to prove her guilty.

Attorney General Lynch sat in her office, along with her top aides, watching Comey deliver his blistering rebuke of Hillary Clinton.

Lynch had promised President Obama and Valerie Jarrett that Hillary would not be indicted. But here was the director of the FBI on national TV laying out what appeared to be an unassailable case for prosecuting her.

How could this have happened? What had gone wrong? Would she be forced to resign?

All these thoughts went through Lynch’s mind, as she later recalled to a friend, as she listened to Comey drone on.

She was livid.

Finally, she couldn’t stand to watch him anymore. She covered her eyes with her hands and let out a string of curses aimed at Jim Comey. And then, three-quarters of the way through his news conference, Comey dropped a bombshell.

Hillary, he said, shouldn’t be prosecuted for her handling of classified information — even though it wasn’t his job to make prosecutorial decisions. That was up to the prosecutors in the Justice Department. There was no evidence, he said, that Hillary had intentionally transmitted or willfully mishandled secret documents in order to harm the United States.

“Our judgment is that no reasonable prosecutor would bring such a case.”

Hillary was clearly guilty as sin, and the right thing would have been for Comey not only to say so — which he did — but to make her pay for her sins.

But he didn’t.