As Donald Trump’s longtime lawyer Michael Cohen shopped around for shadow-lobbying clients early in the Trump era, his pitch included a piece of advice: Stay away from Corey Lewandowski.

Three sources familiar with Cohen’s work say that as he worked to build a business as a Trump-whisperer he wanted potential clients not to sign with Lewandowski, Trump’s former campaign manager and current outside adviser, or other Trumpworld figures trying their hands in Washington’s influence industry.

According to people with knowledge of his pitches, Cohen said he had the ultimate access to President Trump, while Lewandowski wouldn’t be able to get things done. Lewandowski “had a lot of heat on him” Cohen would say, according to one person close to him.

“I have better access than Corey, is how he’d have it known,” one associate told The Daily Beast.

The behind-the-scenes smacktalk didn’t come from nowhere—it was in many ways an outgrowth of a longstanding feud between the two high-profile Trump confidants.

Sources tell The Daily Beast that something akin to a “sibling rivalry” has existed between Cohen and Lewandowski since the beginning of Trump’s 2016 presidential campaign. According to one source familiar with Cohen’s relationship with the president, Trump’s attorney and fixer enjoyed his boss’ trust to the point where he nearly had free reign to conduct himself as he wished during his time in the Trump Organization. This was a source of frustration for years for many people close to Trump, as they watched Cohen get away with things they believed demanded censure.

In the early days of the presidential race, Cohen yearned for, and expected, to be tapped for a larger, official role on Team Trump. Instead, he ended up playing only a marginal one in the campaign. Similarly, after Trump was elected, he had told friends and associates that he was expecting a plum gig in the administration—possibly, even, White House chief of staff. Cohen was not given a White House job, and is currently in the crosshairs of federal investigators.

His relegation to the periphery of Trump’s political inner circle was, in part, orchestrated by Lewandowski. According to sources and campaign vets who know both men, each felt threatened by and deeply suspicious of the other. Cohen also began to feel slighted—betrayed, even—when Trump began treating his new campaign manager with the sort of political favor and affection that Cohen felt he had earned.

Lewandowski, for his part, viewed Cohen as an obstacle to be sidestepped during his ascendance up the ranks of Trump loyalists. Privately, Lewandowski tried to convince Trump that Cohen was a loose cannon, and that his television appearances and shambolic interactions with media outlets—including one where he threatened a Daily Beast reporter in late 2015 while falsely claiming it isn’t legally possible to rape one’s spouse—were actively hurting the future president.

Cohen would later complain privately that all he wanted to do was go on TV to robustly stick up for his friend and boss, and that Lewandowski was thwarting him. What followed was years of resentment, distrust, and bitterness between the two top Trump allies.

Cohen, who created the website “shouldtrumprun.com” in 2011, saw Lewandowski claiming ample credit for the early Trump victories during the 2016 primary.

“It made him furious. Absolutely furious,” a senior 2016 Trump campaign aide recalled to The Daily Beast.

Lewandowski, Cohen, and Cohen’s lawyer did not respond to The Daily Beast’s requests for comment as of press time.

Halfway through the presidential campaign, Lewandowski was sacked after grabbing and bruising a Breitbart News reporter at a Trump campaign event and causing other headaches for the team.

With that, came Cohen’s revenge. According to the book Lewandowski authored with fellow campaign adviser David Bossie, Let Trump Be Trump, Cohen was in the conference room when Donald Trump Jr. broke the news to Lewandowski that he was being ousted from the campaign.

Cohen, according to several campaign staffers, relished being in the room to see his rival axed, and was practically “doing cartwheels, he was so happy,” as one person put it.

Flash-forward to the dawn of the Trump era, when Cohen saw Lewandowski poised to make a killing in the influence industry—and Trump’s personal attorney and pit bull wanted in on the action.

Now, though, it’s Cohen who appears to most immediately have the “heat on him,” as The New York Times reported Tuesday that his former business partner, deposed New York “taxi king” Evgeny Friedman, has struck a deal with federal prosecutors, and Lewandowski who may have the last laugh.

According to a report in The Intercept, Cohen pitched his services during the presidential transition to a former senior official in the Qatari Embassy in Washington. Cohen wanted $1 million to help the official negotiate construction deals in the U.S.

They never signed an agreement. But the following year, the Qatari Embassy signed a $150,000-per-month lobbying deal—later hiked to $500,000-per-month—with the firm Avenue Strategies, which was founded in early 2017 by Lewandowski and fellow Trump campaign alum Barry Bennett. (Lewandowski left the firm in May, before it signed the embassy as a client.)

Bennett said he was puzzled about the services that Cohen was offering potential clients. “He has no knowledge of the workings of Washington, [and] I don’t think he knows how the State Department is structured, or how DoD is structured,” he told The Daily Beast in a brief interview. “I don’t get it. It just goes to show you the full-blown panic on K Street after Donald Trump was elected.”

Cohen never registered as an official lobbyist, instead pitching consulting services that he claimed would help clients navigate Trump’s Washington in ways that avoided work that would trigger public disclosure requirements. But that also legally limited the work he could do, constraining him from, for instance, advocating on clients’ behalf for or against specific federal rules or pieces legislation.

“If he’s not willing to talk to the White House on your behalf, because you’d have to register as a lobbyist to do that, what is Michael Cohen going to tell you?” Bennett wondered. “What tie the president is going to wear today? And how is that of any value?”