President Donald Trump used to "jab at his children with a pole" during family ski trips to get ahead of them as they raced down the mountain, according to a new Atlantic report that documents the budding political rivalry among the Trump children.

Trump sought to cultivate a competitive, ruthless mentality among his children as they grew up, the report says.

Donald Trump Jr., 41, who was once viewed as a liability, is beginning to elbow his way in front of his younger sister Ivanka Trump, according to the report.

Though Ivanka, 37, serves in the Trump administration and has long had her father's favor, Trump Jr. has emerged as a natural representative for the president along the campaign trail.

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President Donald Trump "cultivated a Darwinian dynamic" within his family as his children grew up and, as part of that, would "jab at his children with a pole to get ahead of them" as they raced down the mountain on family ski trips, according to a lengthy report in The Atlantic.

Trump wanted to teach his children to be competitive and suspicious of others — and "sibling rivalry flourished" as a result, spiraling into a battle among his eldest children now to become the president's favorite, the report said.

Read more: Ivanka Trump and Donald Trump Jr. are in a 'cold war' for their father's favor, and suspect each other of planting damaging stories in the media, according to a major new report

Though Ivanka Trump, 37, has always had a close relationship with her father and serves in his administration, her older brother, Donald Trump Jr., 41, has emerged as a de facto spokesman for his father, riling up supporters at rallies across the country and relentlessly defending the president on Twitter.

In short, though Ivanka initially seemed to be the Trump child who might leverage the most with his presidency, Trump Jr. has evolved from being viewed as a liability to a political animal whom his father relies upon along the campaign trail.

Eric Trump has focused more on running the family business than politics. The president's youngest children, Tiffany and Barron, are also on much different paths from Ivanka and Trump Jr.

Read more: Ivanka Trump and her brother Don Jr. are staking opposite sides in the gun control debate — and the president calls Don Jr. his 'gun expert'

Trump Jr. and Ivanka are now engaged in a "cold war" as they squabble for their father's approval, both "paranoid that the other's henchmen" have been "planting damaging stories about them in the press," according to The Atlantic, which cited interviews with White House advisers as well as Trump campaign aides and former employees.