There’s a secret to newly appointed campaign manager Kellyanne Conway’s success with Republican presidential nominee Donald Trump: she knows how to play to his ego.

The notoriously thin-skinned businessman promoted Conway over fellow campaign pollster Tony Fabrizio, in part, because he didn’t like it when Fabrizio told him about his poor poll numbers and how he needed to do better, a source close to the campaign told The Huffington Post.

Conway is better at massaging the truth ― she tells him that there are hidden Trump voters lurking in swing states, the source said ― and her words.

“Kelly’s telling Trump what he wants to hear,” the source said.

“She has a whole vocabulary of diplomatic words. That’s the kind of woman he likes around, who can tell him the soft way ― encourage him, guide him but not criticize him,” said a second source close to Trump.

The Republican pollster doesn’t tell Trump not to say something, she says it would be “unpleasant” or “awkward,” the second source said. She doesn’t say something Trump wants to say is a lie, she says it’s “open to so many interpretations, I want to tighten it up so there’s no room for misinterpretations,” the second source said.

“She’s a genius,” the second source close to Trump told HuffPost. “I get much further telling people what they want to hear. That’s a good way to handle Donald, you reinforce what he wants to do. She is so diplomatic it’s unbelievable.”

But diplomacy, while a useful trait in politics, can be disastrous for a campaign pollster. They are often the campaign’s truth-teller, the one person who will tell the candidate when he or she is failing to connect with voters and should switch tactics. So while an impossibly cheerful spokesperson can help a campaign thrive, an impossibly cheerful pollster presents a unique danger to the candidate.

Going forward, however, Conway will do more than interpret public opinion for Trump. She will help the candidate craft messages designed to appeal to women and independent voters, two groups without which Trump has little chance at making it to the White House.

Neither Conway nor Trump campaign spokeswomen responded to a request for comment.

She's used to dealing with certifiable people ... as long as you follow the crazy rules you can get along perfectly."

Conway has experience working for male politicians who put their feet in their mouths ― she previously worked for failed Senate candidate Todd Akin, a Republican who infamously said that women could not get pregnant from rape if it was a “legitimate rape.”

“She’s used to dealing with certifiable people ... as long as you follow the crazy rules you can get along perfectly,” the second source said.

She has also worked for former House Speaker Newt Gingrich and ran a super PAC aligned with former Trump presidential opponent Sen. Ted Cruz (R-Texas). Conservative donors Robert Mercer and his daughter Rebekah Mercer financed the super PAC.

They reportedly also helped with Conway’s ascension within the Trump campaign. Trump hired Conway in July as a polling strategist, set to work with Fabrizio and then-campaign chairman Paul Manafort, who resigned on Friday. She was hired after a June meeting with Rebekah Mercer, who also had a six-figure check, according to the first source. The campaign is now “Mercer central,” the source said.

Conway is known for advising politicians on how to win over women voters, and has said she does not like Trump’s name-calling.

She laid out her strategy with Trump to The Washington Post in July: to present options, not commands, lest she insult him. She offered an example of the method by talking about convincing her 11-year-old daughter to change from a turquoise outfit to an American flag shade of blue by presenting her with three alternative outfits.

Apparently she takes the same tack with her 70-year-old boss.

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims — 1.6 billion members of an entire religion — from entering the U.S.