Mary L. Trump, President’s Trump’s niece, said that watching the country’s leadership devolve into “a macro version of my incredibly dysfunctional family” was one of the factors that compelled her to write her book, “Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man.”

In an interview Wednesday with The Washington Post, Mary Trump said she blames “almost 100 percent” her grandfather, Fred Trump — the family patriarch whom she describes as a “sociopath” in her 214-page memoir of sorts — for creating the conditions that led to Donald Trump’s rise and, ultimately, what she views as his dangerous presidency.

Much like in her extended family, Mary Trump said, a similar dynamic is now playing out on the national stage, with President Trump simultaneously possessing “an unerring instinct for finding people who are weaker than he is,” while also being “eminently usable by people who are stronger and savvier than he is” and eager to exploit him.

Her book — which was published Tuesday and became an instant bestseller based on advance orders alone — so worried her family that the president’s brother unsuccessfully tried to block its publication in court. Unlike the bevy of other books critical of Trump, this is the only one written by a family member with firsthand knowledge of the Trump clan, and Mary Trump, who earned a doctoral degree in psychology, uses that background to analyze her uncle and his pathologies.

Assessing the current moment, in which Trump has amplified racism and stoked the flames of white grievance and resentment, Mary Trump said that the president is “clearly racist” but that his behavior stems from a combination of upbringing and political cynicism.

“It comes easily to him, and he thinks it’s going to score him points with the only people who are continuing to support him,” she said.

Mary Trump said that growing up in her family, her experience was one of “a knee-jerk anti-Semitism, a knee-jerk racism.”

“Growing up, it was sort of normal to hear them use the n-word or use anti-Semitic expressions,” she said.

Mary Trump, who is gay, added dryly, “Homophobia was never an issue because nobody ever talked about gay people, well, until my grandmother called Elton John” a slur.

Within the Trump family, Fred Trump was the chief enabler. But now in the White House, Mary Trump said, the blame starts with President Trump’s daughter Ivanka and his son-in-law, Jared Kushner — both senior advisers — but expands more broadly to include his “chiefs of staff who went along thinking that they could have some kind of influence, only to find that they didn’t.” Even Senate Majority Leader Mitch McConnell (R-Ky.) is “perfectly willing to put up with all sorts of egregious behavior to get his own agenda through,” she said.

Mary Trump, 55, has long been estranged from her family following a dispute over inheritance, among other things, and is hardly a Donald Trump supporter. She was an unabashed supporter of Hillary Clinton in 2016 and said she plans to vote for former vice president Joe Biden in November, although she supported Sen. Elizabeth Warren (D-Mass.) in the Democratic primaries.

“This is a book of falsehoods, plain and simple,” White House press secretary Kayleigh McEnany said Thursday in response to a request for comment.

Mary Trump opens the book recounting a family dinner at the White House in April 2017, ostensibly to celebrate the birthdays of the president’s sisters, and writes of her family’s stunted dynamic unfolding at 1600 Pennsylvania Ave. Trump’s eldest son, Donald Trump Jr., for instance, offered a toast not for his aunts but for his father, “a sort of campaign speech.”

In the interview, Mary Trump said that at the time, she found it striking that Trump Jr. felt the need “to prop up his father.”

“I’m not entirely sure why someone in Donald’s position, certainly at that time, needed propping up, but he got it anyway,” she said.

At the same dinner, Mary Trump recounts the president turning to Lara Trump — his son Eric’s wife, who had been in a relationship with him for almost eight years at the time — and saying, “I barely even knew who the [expletive] she was, honestly” until she gave a campaign speech supporting him in Georgia.

In the interview, Mary Trump said that no one in the family tried to correct the president or defend Lara Trump; instead, she explained, “people laughed. That’s what we do.”

But the moment was revealing of how the president operates, she said. “It’s sort of his way of making the story bigger, more interesting, but also kind of owning you if you don’t correct him, or he’s aware that you’re aware that he’s lying,” she said. “And it’s a game, and that’s how that night felt.”

Asked about the perception by some that Ivanka Trump is in some ways a steadying force on her father, Mary Trump said that was not her assessment of her cousin in the slightest.

“I think she’s the one who disproves that on an almost-daily basis,” Mary Trump said. “She doesn’t do anything. She spouts bromides on social media, but either she tries to have an impact and fails, or just isn’t interested in having an impact. I can’t think of one thing she’s done to show that she’s moderate or a moderating influence.”

In the book, Mary Trump also recounts an anecdote that President Trump enlisted a smart kid named Joe Shapiro to take the SATs for him. Although Trump was friends with a man named Joe Shapiro at the University of Pennsylvania, the two met once Trump was already in college and had transferred to Penn from Fordham. And both Shapiro’s sister and widow told The Post that in addition to the incorrect timing, he never would have taken a test for anybody, including Trump.

Asked about the discrepancy, Mary Trump said she was not referring to the Joe Shapiro whom Trump met in college, but to another “Joe Shapiro from the neighborhood.”

“I am confident in my source, who is somebody close to Donald,” she said.

In the book, Mary Trump paints a grim and even devastating portrait of both her grandfather and uncle, and she said that nothing Trump has done since taking office has shocked her.

When pressed, she said that not even the president’s incendiary — at times racist and misogynistic — language, or even his immigration policy separating children and families at the nation’s southern border has surprised her. “No, the more divisive, the better, the cooler,” she said, explaining what she views as the president’s ethos.

Mary Trump writes that she considered coming forward to try to stop Trump’s election during the summer of 2016 and ultimately decided against doing so — a decision she doesn’t regret, in part because she believes nothing could have prevented his election then.

Now, however, she is hoping the fortuitous timing of her book — which was originally scheduled for release in April — could help impact the November election. And either way, she said, she wants to feel like she did her small part to warn the nation about what she views as the dangers of her uncle.

“I’d seen enough in the last few years to know that no one thing is going to make a bit of difference,” she said. “This is going to be — using the expression loosely — death by a thousand lashes, right, and maybe in this case it’s going take a million lashes, so it’s more about adding to the record of egregious things that have happened and for which there has been no accountability.”

She continued: “But more than that, I also felt a responsibility to make sure that people are as informed as possible when November comes, because I do not believe that was the case in 2016 at all.”

For now, she said she views this book as her small bit of activism and prefers not to focus on the November election — or the possibility that Trump could win reelection.

If that happens, she said with a laugh, “I may be in the Caribbean.”