Efforts by a throng of women at NBC to defend legendary newsman Tom Brokaw against sexual harassment allegations may have backfired.

Apparently not all female employees were on board with the idea of signing a “women’s letter,” defending the embattled former “NBC Nightly News” anchor. Page Six quotes female staffers who said they felt “under huge pressure” by female superiors to sign the letter.

NBC stars Rachel Maddow, Mika Brzezinski, Andrea Mitchell and Maria Shriver (still a “Today” show correspondent) rushed to sign the letter last week, touting Brokaw’s support of women in the NBC workplace and calling him “a man of tremendous decency and integrity,” Page Six reported.

The letter was prompted by reports last Thursday in the Washington Post and Variety, in which two former network employees, including one-time foreign correspondent Linda Vester, claimed that the “NBC Nightly News” anchor had harassed them in the 1990s.

More than 100 other women at NBC joined Maddow, Mitchell and Brzezinski in signing the letter for Brokaw. But some of the signatories said they felt “forced” to affix their names to the document.

“We had no choice, particularly the lower level staffers,” an NBC staffer told Page Six. “The letter was being handed around the office and the unspoken threat was that if your name was not on it, there would be some repercussion down the road. Execs are watching to see who signed and who didn’t. This was all about coming out in force to protect NBC’s golden boy; the network’s reputation is tied to Brokaw . . . If more women come forward, that’s a big problem.”

Another insider told Page Six that the powerful names on the letter could intimidate other victims.

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“When you have over 100 women like Andrea Mitchell signing a letter of support without knowing the facts, it’s pretty scary,” the source said. “The letter will have a chilling effect on other women coming forward.”

The 78-year-old Brokaw has vehemently denied harassing Vester and the other woman, a former production assistant who asked to remain anonymous.

Brokaw has not yet responded to claims by a third woman that he made the moves on her 50 years ago, when they were both working as journalists in Los Angeles in the early 1960s and he was newly married to his wife Meredith Lynn Auld. In the New York City-based publication The Villager, Mary Reinholz said Brokaw tried to kiss her outside her rented L.A.- home after helping her with a story she was working on.

“I pulled away, reminding him that he was married and a tryst was out of the question,” Reinholz wrote. “He said, ‘Yes, it would be unfair to Meredith,’ meaning his wife.”

In a dramatically-written email distributed to NBC colleagues and obtained by The Hollywood Reporter, Brokaw ripped into the reports by the Washington Post and Variety. He said he was being falsely depicted as an “avatar of male misogyny, taken to the guillotine and stripped of any honor and achievement I had earned in more than a half century of journalism and citizenship.”

In saying the allegations left him “hurt” and “angry,” he denied he had ever attempted to force himself on Vester in encounters that both he and Vester said took place in a hotel room and in her apartment.

Brokaw recalled having a cordial working relationship with Vester and wrote that he helped her get a job with Roger Ailes at Fox News. He characterized her as having had limited success at NBC News and a modest career at Fox and suggested she had a grudge against NBC because she had failed “in her pursuit of stardom.”

The women’s letter does not directly address the allegations against Brokaw. Instead it offers a character reference, hailing him as someone who has treated “each of us with fairness and respect.” The letter also said Brokaw had given women “opportunities for advancement and championed our successes throughout our careers.”

One female NBC star who presumably didn’t sign the letter was “Today” host Megyn Kelly, according to another report in Page Six. On her show on Monday, she warned her female colleagues who are defending Brokaw, saying, “You don’t know what you don’t know.”

Kelly also pointed out that the letter is just a character reference, not proof that he didn’t behave less than honorably with other women.

“They’re saying, ‘For what it’s worth, my experience with him has always been honorable, and he’s always treated me well.’ And I understand that because when you love the person being under attack, you want to say, ‘This has been my experience.'”

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Kelly cited her own experience with the late Fox News CEO Ailes, whom she accused of sexually harassing her. She said Ailes had female colleagues at Fox who defended him — based on their own experience — amid an internal sexual harassment investigation. Ailes resigned from his job in July 2016.

Kelly said she wasn’t impugning Brokaw, whom she said she loves and “who’s been so good to me.” She added, “Just saying, you don’t know what you don’t know.”

A representative at NBC told Page Six that the women’s letter is “a purely grass-roots effort, led by women outside of the company who are motivated by their own support for Tom Brokaw.” The spokesperson said management “has played absolutely no role whatsoever.”

Page Six noted that the letter-signing campaign was led by Goldman Sachs executive Liz Bowyer, who produced the “Tom Brokaw Reports” docu-series and worked on two of the anchor’s books.