WASHINGTON — (CNN) Long before Donald Trump ever became a credible presidential candidate, let alone the commander in chief, the former reality TV star was guided by one animating principle: “If they screw you, screw them back 10 times as hard.”

Trump’s desire for revenge played out in public on Thursday when, in an effort to spook conservative members of his own party, the President lumped the Freedom Caucus — a collection of conservative Republican lawmakers — with Democrats and pledged to “fight them” in 2018.

Trump and his White House feel betrayed by the conservative Republicans. Many backed Trump early in the 2016 campaign and stood by him during some of the toughest trials of the campaign. But when it came to passing his first conservator legislative goal — health care reform — the conservatives revolted en masse and killed the bill.

Trump’s top emissaries also made this case directly to lawmakers. Rep. Mark Sanford, a South Carolina Republican, told Charleston’s Post and Courier Thursday that White House budget chief Mick Mulvaney, a former Palmetto State congressman, told him: “The President asked me to look you square in the eyes and to say that he hoped that you voted ‘no’ on this bill so he could run (a Republican primary challenger) against you in 2018.”

Trump himself singled out three congressmen by name Thursday afternoon on Twitter.

Where are @RepMarkMeadows, @Jim_Jordan and @Raul_Labrador?#RepealANDReplace #Obamacare

— Donald J. Trump (@realDonaldTrump) March 30, 2017

According to sources close to the Trump administration, top officials had wanted to have a vote on the health care bill — even if it was bound to fail — so that Republicans bucking Trump would be forced to go on the record and give the White House a list of lawmakers to exact revenge on.

The spirit of the move was pure Trump.

“If someone screws you, screw them back 10 times harder,” Trump, sporting a pink tie and dark suit, told business leaders during a 2005 speech in Colorado. “At least they’re going to leave you alone, and at least you’ll feel good.”

He added: “I believe in screwing people when they screw you.”

The speech, which was covered by local press at the time for its “blunt” language, tracks with much of what Trump has said and written during his career.

Speaking in Sydney, Australia, in 2011, Trump said again: “Get even with people. If they screw you, screw them back 10 times as hard. I really believe that.”

“I fight when I feel I’m getting screwed, even if it’s costly and difficult and highly risky,” Trump wrote in “The Art of the Deal,” his 1987 book.

[van id=”politics/2017/03/27/dave-brat-health-care-trump-nr.cnn”]

And in his 2009 book, “Think Big,” Trump wrote: “I love getting even when I get screwed by someone. … Always get even. When you are in business you need to get even with people who screw you. You need to screw them back 15 times harder. You do it not only to get the person who messed with you but also to show the others who are watching what will happen to them if they mess with you. If someone attacks you, do not hesitate. Go for the jugular.”

This desire to get even also played out during the 2016 campaign.

“What happens is they hit me and I hit them back harder,” Trump told Fox News in April 2016. “But they hit me and I hit them back harder and they disappear. That’s what we want to lead the country.”

When Khizr and Ghazala Khan, the parents of an Army captain killed in Iraq, slammed Trump’s proposed Muslim ban during the 2016 Democratic National Convention, the Republican nominee went after the couple.

“Mr. Khan, who has never met me, has no right to stand in front of millions of people and claim I have never read the Constitution, (which is false) and say many other inaccurate things,” Trump said in a statement after suggesting Ghazala Khan said nothing during the DNC speech because she wasn’t allowed to.

When criticized for going after the Khans, Trump defended his comments by arguing he was just getting even.

“I was viciously attacked by Mr. Khan at the Democratic Convention. Am I not allowed to respond,” Trump tweeted.

Trump’s desire for revenge is a tendency that has long been nursed, fostered and perfected by the business leader over decades and stems from guidance he received from Roy Cohn, Trump’s lawyer-turned-mentor.

Cohn, who first met Trump in 1973, was known as a no-holds-barred lawyer who was chief counsel for Sen. Joseph McCarthy’s inquiry into communism early in his career and maintained a dubious list of clients later in his career at a top New York lawyer.

Cohn first represented Trump when the Justice Department accused the young real estate developer and his father, Fred Trump, of housing discrimination in 1973. Cohn responded to the Justice Department suit by filing a $100 million countersuit against the government.

The countersuit was thrown out, and two years later the Trumps settled. But the case cemented the philosophy that Trump would co-opt: Always hit back harder and never admit defeat.

Alan Dershowitz, a lawyer who became acquaintances after working with Cohn, said much of what animates Trump could be traced back to Cohn’s philosophies.

“Never apologize, be loyal to your friends, put ideology behind pragmatism, those are all the things were Roy Cohn’s hallmarks,” Dershowitz said. “He had many attributes in common with Trump.”

Dershowitz added that Cohn believed in punching back hard when enemies attacked, something Trump has long discussed in books and speeches.

“He divided the world to whether you were on his side or were you an enemy,” Dershowitz said, “and believed you never give your enemies a victory.”

The-CNN-Wire ™ & © 2017 Cable News Network, Inc., a Time Warner Company. All rights reserved. (PHOTO: Pool/CNN)