President Donald Trump prizes two qualities above all else: loyalty and discretion—don’t cross the boss, and don’t leak. Whether he’ll find either in his new communications director is an open question.

On Sunday, New York investor and media personality Anthony Scaramucci declared that he will root out White House leakers in his new post. “We’re going to stop the leaks. And if we don’t stop the leaks, I’m going to stop you. It’s just really that simple,” he said on an appearance on CNN’s State of the Union.

But aides to 2016 presidential candidates whom Scaramucci endorsed before coming around to Trump say he was suspected of leaking internal information, and left out of some internal discussions for fear that he would pass along those sorts of details to reporters—or that he already had.

Scaramucci did not respond to questions about this story.

He threw his weight behind the Trump campaign only after his first two preferred candidates, Wisconsin Gov. Scott Walker and former Florida governor Jeb Bush, dropped out. Between his stints raising money for those campaigns, he was in talks with a third, that of Florida Sen. Marco Rubio.

Former senior aides on all three of those campaigns say Scaramucci gave the impression of a hanger-on trying to methodically get in the good graces of whichever candidate he saw as most likely to prevail. Only when Trump had the nomination all but secured did Scaramucci sign on with his campaign.

“He was trying to pick the winner,” according to a former senior Rubio aide, who said Scaramucci approached that campaign after Walker withdrew from the race in September 2015. Despite intense competition to pick up the support of key fundraisers, the former Rubio aide said, Scaramucci was seen as too self-serving and untrustworthy, and the Rubio campaign declined his support.

Talk of his shifting loyalties was already circulating among Republicans on various sides of the primary due to rumors emanating from the disbanded Walker campaign that Scaramucci had leaked information to the press and otherwise caused headaches for the campaign.

“He was suspected of leaking and stirring up drama with the donors,” a former senior Walker campaign aide recalled.

Another senior Walker aide said Scaramucci was suspected of airing some of the campaign’s dirty laundry. “There were a lot of people unhappy with how the campaign was being managed. It wouldn’t surprise me if he was stoking those things with the press.”

Scaramucci’s reputation in GOP political circles as a press leaker may have originated in 2012, when he tipped off a Bloomberg reporter to the time and location of a fundraising event for the Republican super PAC Crossroads GPS, according to a report in Politico at the time. At the event, Crossroads chief Karl Rove made disparaging remarks about then-GOP Senate candidate Todd Akin, who was under fire for comments questioning whether a woman could be impregnated by rape.

The comments, which were posted by Bloomberg, were immensely embarrassing for Rove, who apologized to Akin. Scaramucci, in turn, apologized to Rove.

Beyond his apparent penchant for leaking, both Walker aides say Scaramucci appeared to be laying the groundwork for his jump from the Walker campaign. Trump officially entered the race in June. Within months, the aides say, Scaramucci had met with Trump even as he fundraised for Walker, raising questions about his loyalties.

After the first Republican presidential debate in August 2015, the Walker aides said, Scaramucci met with Trump at his New York campaign headquarters. That meeting “was always curious,” one of the Walker aides said.

When the meeting was discovered, rumors flew internally that Scaramucci was going to be jumping ship for the Trump campaign. Things were already starting to go awry for Walker—his campaign was burning through money at an unsustainable rate—and the rumors became an “unnecessary distraction,” one of the Walker aides said.

That talk was quickly tamped down, the aide noted, and Walker’s team was assured that “he wasn’t switching and it was just rumors.” But “looking back at the arc of this guy’s conduct, it certainly raises some more questions as to what really transpired.”

“He seems like a ladder climber to me,” the aide said, “someone who’s in it for his self-interest.”

That’s certainly nothing new in politics, but even among campaigns scrambling to secure high-dollar financial support in the early stages of the presidential campaign, Scaramucci was seen as too untrustworthy.

When Walker withdrew from the race in September 2015, Scaramucci didn’t jump directly to the Trump campaign. First he offered his services to Rubio, the former aide to that campaign recalled, before signing on with Bush, Rubio’s home state nemesis.

Bush aides say they were acutely aware of Scaramucci’s reported conduct on the Walker campaign.

Scaramucci “had a reputation for leaking that we were cognizant of,” Tim Miller, the Bush campaign’s communications director, told The Daily Beast. Scaramucci was reportedly left out of discussions with other campaign fundraisers out of a concern that he would leak to the press.

In spite of that reputation, Scaramucci has now taken on the mantle of internal White House anti-leak enforcer. And he has professed his extreme loyalty to the president despite a reputation for hedging his political bets.

Scaramucci joked about his late Trump endorsement during a White House press briefing on Friday, when he was officially given the White House communications director post. “He brings it up every 15 seconds,” he said of Trump. But “I’m a team player,” Scaramucci added. “I believe you have to subordinate yourself to the greater good of the team.”

The president tweeted a defense of his new top communications aide. Scaramucci “wanted to endorse me 1st, before the Republican Primaries started, but didn't think I was running!" the Trump wrote.

In fact, Trump had been in the race for nearly a year before Scaramucci got behind his candidacy. The new White House communications director had taken a litany of policy positions contrary to the president’s agenda. He has financially backed some of the president’s most aggressive antagonists. And he had even taken shots at Trump himself.

“I was an inexperienced person in the world of politics,” Scaramucci told reporters on Friday of some of his past Trump criticism. “I was supporting another candidate. I should have never said that about him. So Mr. President, if you’re listening, I personally apologize for the 50th time for saying that.”

While that was likely the answer Trump was looking for, Scaramucci’s reputation for leaks and allegiance-shifting seems to deviate from what the president has generally sought in his top aides.

The president commands loyalty. Scaramucci, one of the Walker aides remarked, exudes a “pretty self-serving personality.”