Sharyl Attkisson is an unreasonable woman. Important people have told her so.

When the longtime CBS reporter asked for details about reinforcements sent to the Benghazi compound during the Sept. 11, 2012 terrorist attack, White House national security spokesman Tommy Vietor replied, “I give up, Sharyl . . . I’ll work with more reasonable folks that follow up, I guess.”

Another White House flack, Eric Schultz, didn’t like being pressed for answers about the Fast and Furious scandal in which American agents directed guns into the arms of Mexican drug lords. “Goddammit, Sharyl!” he screamed at her. “The Washington Post is reasonable, the LA Times is reasonable, The New York Times is reasonable. You’re the only one who’s not reasonable!”

Two of her former bosses, CBS Evening News executive producers Jim Murphy and Rick Kaplan, called her a “pit bull.”

That was when Sharyl was being nice.

Now that she’s no longer on the CBS payroll, this pit bull is off the leash and tearing flesh off the behinds of senior media and government officials. In her new memoir/exposé “Stonewalled: My Fight for Truth Against the Forces of Obstruction, Intimidation, and Harassment in Obama’s Washington” (Harper), Attkisson unloads on her colleagues in big-time TV news for their cowardice and cheerleading for the Obama administration while unmasking the corruption, misdirection and outright lying of today’s Washington political machine.

‘Not until the stock split’

Calling herself “politically agnostic,” Attkisson, a five-time Emmy winner, says she simply follows the story, and the money, wherever it leads her.

In nearly 20 years at CBS News, she has done many stories attacking Republicans and corporate America, and she points out that TV news, being reluctant to offend its advertisers, has become more and more skittish about, for instance, stories questioning pharmaceutical companies or car manufacturers.

Working on a piece that raised questions about the American Red Cross disaster response, she says a boss told her, “We must do nothing to upset our corporate partners . . . until the stock splits.” (Parent company Viacom and CBS split in 2006).

Often [network executives] dream up stories beforehand and turn the reporters into “casting agents”

Meanwhile, she notes, “CBS This Morning” is airing blatant advertorials such as a three-minute segment pushing TGI Fridays’ all-you-can-eat appetizer promotion or four minutes plugging a Doritos taco shell sold at Taco Bell.

Reporters on the ground aren’t necessarily ideological, Attkisson says, but the major network news decisions get made by a handful of New York execs who read the same papers and think the same thoughts.

Often they dream up stories beforehand and turn the reporters into “casting agents,” told “we need to find someone who will say . . .” that a given policy is good or bad. “We’re asked to create a reality that fits their New York image of what they believe,” she writes.

Reporting on the many green-energy firms such as Solyndra that went belly-up after burning through hundreds of millions in Washington handouts, Attkisson ran into increasing difficulty getting her stories on the air. A colleague told her about the following exchange: “[The stories] are pretty significant,” said a news exec. “Maybe we should be airing some of them on the ‘Evening News?’ ” Replied the program’s chief Pat Shevlin, “What’s the matter, don’t you support green energy?”

Says Attkisson: That’s like saying you’re anti-medicine if you point out pharmaceutical company fraud.

A piece she did about how subsidies ended up at a Korean green-energy firm — your tax dollars sent to Korea! — at first had her bosses excited but then was kept off the air and buried on the CBS News Web site. Producer Laura Strickler told her Shevlin “hated the whole thing.”

‘Let’s not pile on’

Attkisson mischievously cites what she calls the “Substitution Game”: She likes to imagine how a story about today’s administration would have been handled if it made Republicans look bad.

In green energy, for instance: “Imagine a parallel scenario in which President Bush and Vice President Dick Cheney personally appeared at groundbreakings for, and used billions of tax dollars to support, multiple giant corporate ventures whose investors were sometimes major campaign bundlers, only to have one (or two, or three) go bankrupt . . . when they knew in advance the companies’ credit ratings were junk.”

Attkisson continued her dogged reporting through the launch of ObamaCare: She’s the reporter who brought the public’s attention to the absurdly small number — six — who managed to sign up for it on day one.

One of her bosses had a rule that conservative analysts must always be labeled conservatives, but liberal analysts were simply “analysts.”

“Many in the media,” she writes, “are wrestling with their own souls: They know that ObamaCare is in serious trouble, but they’re conflicted about reporting that. Some worry that the news coverage will hurt a cause that they personally believe in. They’re all too eager to dismiss damaging documentary evidence while embracing, sometimes unquestioningly, the Obama administration’s ever-evolving and unproven explanations.”

One of her bosses had a rule that conservative analysts must always be labeled conservatives, but liberal analysts were simply “analysts.” “And if a conservative analyst’s opinion really rubbed the supervisor the wrong way,” says Attkisson, “she might rewrite the script to label him a ‘right-wing’ analyst.”

In mid-October 2012, with the presidential election coming up, Attkisson says CBS suddenly lost interest in airing her reporting on the Benghazi attacks. “The light switch turns off,” she writes. “Most of my Benghazi stories from that point on would be reported not on television, but on the Web.”

Two expressions that became especially popular with CBS News brass, she says, were “incremental” and “piling on.” These are code for “excuses for stories they really don’t want, even as we observe that developments on stories they like are aired in the tiniest of increments.”

Hey, kids, we found two more Americans who say they like their ObamaCare! Let’s do a lengthy segment.

Friends in high places

When the White House didn’t like her reporting, it would make clear where the real power lay. A flack would send a blistering e-mail to her boss, David Rhodes, CBS News’ president — and Rhodes’s brother Ben, a top national security advisor to President Obama.

The administration, with the full cooperation of the media, has successfully turned “Benghazi” into a word associated with nutters, like “Roswell” or “grassy knoll,” but Attkisson notes that “the truth is that most of the damaging information came from Obama administration insiders. From government documents. From sources who were outraged by their own government’s behavior and what they viewed as a coverup.”

Similarly, though the major media can’t mention the Fast and Furious scandal without a world-weary eyeroll, Attkisson points out that the story led to the resignation of a US attorney and the head of the ATF and led President Obama to invoke for the first time “executive privilege” to stanch the flow of damaging information.

Attkisson, who received an Emmy and the Edward R. Murrow award for her trailblazing work on the story, says she made top CBS brass “incensed” when she appeared on Laura Ingraham’s radio show and mentioned that Obama administration officials called her up to literally scream at her while she was working the story.

One angry CBS exec called to tell Attkisson that Ingraham is “extremely, extremely far right” and that Attkisson shouldn’t appear on her show anymore. Attkisson was puzzled, noting that CBS reporters aren’t barred from appearing on lefty MSNBC shows.

She was turning up leads tying the Fast and Furious scandal (which involved so many guns that ATF officials initially worried that a firearm used in the Tucson shooting of Congresswoman Gabrielle Giffords might have been one of them) to an ever-expanding network of cases when she got an e-mail from Katie Couric asking if it was OK for Couric to interview Eric Holder, whom Couric knew socially, about the scandal. Sure, replied Attkisson.

No interview with Holder aired but “after that weekend e-mail exchange, nothing is the same at work,” Attkisson writes. “The Evening News” began killing her stories on Fast and Furious, with one producer telling Attkisson, “You’ve reported everything. There’s really nothing left to say.”

Readers are left to wonder whether Holder told Couric to stand down on the story.

No investigations

Attkisson left CBS News in frustration earlier this year. In the book she cites the complete loss of interest in investigative stories at “CBS Evening News” under new host Scott Pelley and new executive producer Shevlin.

She notes that the program, which under previous hosts Dan Rather, Katie Couric and Bob Schieffer largely gave her free rein, became so hostile to real reporting that investigative journalist Armen Keteyian and his producer Keith Summa asked for their unit to be taken off the program’s budget (so they could pitch stories to other CBS News programs), then Summa left the network entirely.

When Attkisson had an exclusive, on-camera interview lined up with Nakoula Basseley Nakoula, the YouTube filmmaker Hillary Clinton blamed for the Benghazi attacks, CBS News president Rhodes nixed the idea: “That’s kind of old news, isn’t it?” he said.

Attkisson is a born whistleblower, but CBS lost interest in the noise she was making.

Sensing the political waters had become too treacherous, Attkisson did what she thought was an easy sell on a school-lunch fraud story that “CBS This Morning” “enthusiastically accepted,” she says, and was racing to get on air, when suddenly “the light switch went off . . . we couldn’t figure out what they saw as a political angle to this story.”

The story had nothing to do with Michelle Obama, but Attkisson figures that the first lady’s association with school lunches, and/or her friendship with “CBS This Morning” host Gayle King, might have had something to do with execs now telling her the story “wasn’t interesting to their audience, after all.”

A story on waste at the Department of Housing and Urban Development, planned for the CBS Weekend News, was watered down and turned into a “bland non-story” before airing: An exec she doesn’t identify who was Shevlin’s “number two,” she says, “reacted as if the story had disparaged his best friend. As if his best friend were Mr. Federal Government. ‘Well, this is all the states’ fault!’ . . . he sputtered.”

Meanwhile, she says, though no one confronted her directly, a “whisper campaign” began; “If I offered a story on pretty much any legitimate controversy involving government, instead of being considered a good journalistic watchdog, I was anti-Obama.”

Yet it was Attkisson who broke the story that the Bush administration had once run a gun-walking program similar to Fast and Furious, called Wide Receiver. She did dozens of tough-minded stories on Bush’s FDA, the TARP program and contractors such as Halliburton. She once inspired a seven-minute segment on “The Rachel Maddow Show” with her reporting on the suspicious charity of a Republican congressman, Steve Buyer.

Attkisson is a born whistleblower, but CBS lost interest in the noise she was making.

‘They’ll sacrifice you’

Ignoring Attkisson proved damaging to CBS in other ways. When a senior producer she doesn’t identify came to her in 2004 bubbling about documents that supposedly showed then-President George W. Bush shirked his duties during the Vietnam War, she took one look at the documents and said, “They looked like they were typed by my daughter on a computer yesterday.”

Asked to do a followup story on the documents, she flatly refused, citing an ethics clause in her contract. “And if you make me, I’ll have to call my lawyer,” she said. “Nobody ever said another word” to her about reporting on the documents, which turned out to be unverifiable and probably fake.

After Pelley and Shevlin aired a report that wrongly tarnished reports by Attkisson (and Jonathan Karl of ABC News) on how the administration scrubbed its talking points of references to terrorism after Benghazi, and did so without mentioning that the author of some of the talking points, Ben Rhodes, was the brother of the president of CBS News, she says a colleague told her, “[CBS] is selling you down the river. They’ll gladly sacrifice your reputation to save their own. If you don’t stand up for yourself, nobody will.”

After reading the book, you won’t question whether CBS News or Attkisson is more trustworthy.