Rather, these people said, the goal is to sow public doubt about Mueller and his prosecutors in advance of upcoming criminal trials — and to give the president political cover if he wants to start issuing pardons to any current or former aides swept up in the Russia scandal.

“It is definitely a smarter strategy than outright firing of Mueller, because that is likely to create a firestorm,” said Elizabeth de la Vega, a former assistant U.S. attorney from the Northern District of California. “It is also entirely consistent with Trump’s modus operandi because he is surprisingly nonconfrontational, preferring to be manipulative and, frankly, sneaky.”

The latest complaints against Mueller are a sharp escalation from earlier this year, when Trump and his allies took theirfirst shots at the former FBI director, questioning his hiring of prosecutors who had predominantly donated to Democratic politicians, including President Barack Obama and Hillary Clinton.

Their grievances have taken on an added sense of political urgency as the Russia inquiry creeps closer to the president’s inner circle. Earlier this month, former national security adviser Michael Flynn pleaded guilty to lying to investigators about his contact with foreign officials. The plea followed a similar deal cut by former campaign adviser George Papadopoulos in October, when former Trump campaign manager Paul Manafort and his deputy, Rick Gates, pleaded not guilty on charges including tax evasion.

Mueller’s critics have especially latched on to two major revelations from the past week. First, the Justice Department released to Congress and reporters several hundred anti-Trump text messagesexchanged between two FBI officials who had previously served on Mueller’s team. Then on Saturday, an attorney for Trump’s transition teamlodged a complaint that the special counsel had improperly obtained tens of thousands of the team’s emails directly from the General Services Administration — claiming violations of both attorney-client privilege and the Fourth Amendment, which protects against unlawful search and seizure.

While Trump told reporters Sunday as he returned from Camp David that he wasn’t considering firing Mueller, he did respond when asked about the special counsel’s methods for obtaining his transition team’s emails.

“Not looking good,” Trump said. “It’s not looking good. It’s quite sad to see that. My people are very upset about it. I can’t imagine there’s anything on them, frankly, because as we said, there’s no collusion.”

Several legal experts described Mueller’s moves as entirely appropriate, and the special counsel’s office even defended itself through a rare public comment.

“When we have obtained emails in the course of our ongoing criminal investigation, we have secured either the account owner’s consent or appropriate criminal process,” Mueller spokesman Peter Carr said in a statement released after midnight on Sunday.

For Trump, launching direct attacks against Mueller has up to now been a no-no. While the businessman-turned-politician used his branding skills to great effect during his historic 2016 presidential campaign — labeling opponents with catchy monikers like “Little Marco,” “Lyin’ Ted” and “Crooked Hillary” — he has so far heeded the advice of White House attorney Ty Cobb and other aides who have urged him to leave Mueller alone.

But how long that lasts is an open question.

Some of the very public voices Trump listens to the most are beating the drum that Mueller’s investigation has gone off the rails. The Wall Street Journal earlier this month published an op-ed asserting that the special counsel was “too conflicted to investigate the FBI” and urging him to “step down in favor of someone more credible.”

Fox News host Jeanine Pirro, who is scheduled to appear with the president’s son Eric in mid-January at a Mar-a-Lago event in South Florida celebrating the one-year anniversary of Trump’s inauguration, alsounloaded on the Russia investigators during a recent program.

“There is a cleaning needed in our FBI and Department of Justice,” she said “It needs to be cleansed of individuals who should not just be fired, but who need to be taken out in cuffs!”

Jay Sekulow, the president’s personal attorney, used an appearance last week on Sean Hannity’s Fox show to call for a second special counsel to look into potential conflicts of interest between the Justice Department and the FBI. And then Hannity, a few days later and again with Sekulow on the program as a guest, took a direct swing at the Mueller probe. “They have been exposed as corrupted, abusively biased, incapable of conducting a fair investigation,” he said.

Mark Corallo, a former Justice spokesman when John Ashcroft was attorney general who earlier this year worked as press secretary for Trump’s legal team, said in an interview with POLITICO that he’s tried to avoid direct attacks on Mueller — until the FBI officials’ emails surfaced.

Now, he’s accusing some on Mueller’s team of “not just hyperpartisanship, but what seems to be actual efforts to go after Trump and his associates without the objectivity that is required of prosecutors and investigators.”

Corallo said Trump would be making a “colossal mistake” in firing the special counsel.

“It’d certainly lead to serious talk of impeachment,” he said, adding that talk about pardons for now was premature “until the Mueller investigation has wrapped up.”

But Corallo predicted that because of recent events, Mueller investigators were going to suffer in the court of public opinion.

“Whether or not the facts that underpin the Flynn, Manafort and Gates charges are legitimate or not is now irrelevant to a large portion of the American people,” he said.

Indeed, public opinion on the Mueller investigation remains a mixed bag. A POLITICO/Morning Consultpoll of 1,955 registered voters conducted Dec. 8-11 — just before therelease of the FBI officials’ anti-Trump text messages — found 39 percent of respondents saying the special counsel had been conducting a fair investigation, with 27 percent saying it hadn’t been fair and another 34 percent who said they didn’t know or held no opinion.

The same poll did suggest Trump could be entering dangerous terrain if he fired Mueller: Forty-six percent said that would not be a good idea, while 19 percent approved of the president’s ousting the special counsel. Thirty-five percent had no opinion or said they didn’t know.

Several sources closely tracking the Russia investigation said the mixed messages coming out of Trump’s camp are happening for a reason.

“The collective criticism of Mueller and his staff, the truly bizarre complaint to Congress from the transition team — are we cooperating or not? — and the calls for a second special counsel are clearly part of an orchestrated strategy to try to discredit Mueller and, in turn, to potentially lay the groundwork to justify a pardon for Flynn,” a white-collar attorney representing a senior Trump aide wrote in an email to POLITICO.

“Whether Trump actually pulls the trigger will depend, in part, on what sort of feedback they get from this barrage of trial balloons,” the lawyer added. “But — not to mix metaphors too awfully — this is plainly a shot across the bow.”

Trump so far has brushed aside questions about pardons, even though some of his most loyal aides have landed directly in Mueller’s cross hairs.

“I don’t want to talk about pardons for Michael Flynn yet,” the president told reporters on Friday. “We’ll see what happens. Let’s see.”

That open-ended response prompted panic among some Trump critics. The ranking member of the House Judiciary Committee, Democratic Rep. Jerrold Nadler of New York, and the panel’s full slate of Democrats wrote a letter to their Republican counterparts on Monday urging them to hold hearings on the president’s pardon powers.

Mueller’s defenders see the attacks in a more nefarious light.

“It’s all such a bunch of poppycock. It’s just feeding his base. I don’t understand how people buy it,” said Katya Jestin, a former Justice Department prosecutor who tried a Mafia case with Mueller attorney Andrew Weissmann and later worked with him in private practice at Jenner & Block.

“I think it’s a distraction,” she added. “I feel this gets ginned up every time they think something is coming down the pike.”

Barbara McQuade, a former Obama administration U.S. attorney from eastern Michigan, said the anti-Mueller attacks looked to be part of a long-term strategy to discredit the special counsel.

“This could be to lay the groundwork for firing him, but it seems more likely to me to be a strategy to cast doubt on any charges that Mueller files down the road,” she said. “Putting the police on trial in this way is a common tactic of criminal defense attorneys. If the public is conditioned to doubt the credibility of Mueller, then the public may also doubt the validity of the charges themselves.”