If Donald Trump was sending smoke signals last week when he publicly attacked Robert Mueller, his allies appear to have gotten the message. Trump’s frustration boiled over when Mueller crossed one of his “red lines” by issuing a subpoena for Trump Organization records, convincing the president to abandon the conciliatory approach long advocated by his attorneys. “Why does the Mueller team have 13 hardened Democrats, some big Crooked Hillary supporters, and Zero Republicans?” he seethed on Twitter. Within hours, Politico notes, the Drudge Report was promoting a story blaming Mueller for the F.B.I.’s bungled investigation into the 2001 anthrax scare, which took place on his watch as director, and had launched a live poll on whether Trump should fire Mueller. (After more than a week, 76 percent of readers supported the move.) Pro-Trump journalist Sara Carter wrote an article accusing Mueller of protecting Mafia informant Whitey Bulger when he served as a federal prosecutor in Boston during the 1980s—and was promptly brought on to Fox News to debrief Sean Hannity. And Adam Gingrich, who worked for the Trump campaign in Pennsylvania, incited a Twitter crusade among conservatives with the hashtags #RiseUp and #FireMueller.

Some say the barrage appears to have been coordinated. “It looks like the beginnings of a campaign,” a source familiar with Trump’s legal strategy told Politico. “It looks like they are trying to seed the ground. Ultimately if the president determines he wants to fire Mueller he’s going to want to make sure there’s ample public record that he can fall back on.” The focus on older incidents, in particular, bears the hallmarks of professional opposition research.

Tarring Mueller is not a new strategy, but it may be the only weapon in Trump’s arsenal. The special counsel has been marching forward methodically, investigating dozens of people and incidents on the periphery of the Russian collusion question as his team draws closer to the president. Firing Mueller, while a possibility, would incite a political firestorm that could consume Trump’s presidency. The next best thing is to destroy his credibility in the public eye, or at least among fellow Republicans, in anticipation of charges that could precipitate his impeachment if Democrats retake the House next year. Perhaps most important, from a legal standpoint, is the fact that Trump’s participation would hardly be necessary to orchestrate such a campaign—his most recent Twitter attack, in which he finally named the special counsel, could be seen as a green light. “This anti-Mueller wave feels different because it is being driven directly by the president,” Kurt Bardella, a former spokesman for Breitbart News, told Politico. “They don’t need to have a conversation or a meeting or a memo. They know once that signal comes they’re free to, as Steve Bannon would say, ‘Go buck wild.’”

An increased level of agitation has some on alert for more serious moves against Mueller. On Tuesday, Senators Chris Coons, a Democrat, and Thom Tillis, a Republican, issued statements urging Trump to allow Mueller to complete his probe. Shortly afterward, 9 out of 10 Democrats on the Senate Judiciary Committee signed a letter to five Justice Department officials who would be involved in overseeing the investigation if Deputy Attorney General Rod Rosenstein resigns, calling for a “written and public commitment” that they will not interfere with Mueller’s work. Both Speaker of the House Paul Ryan and Senate Majority Leader Mitch McConnell previously offered comments in support of Mueller, though they stopped short of calling for legislation to protect him.

The heightened attacks come at a critical point in the Mueller investigation. Over the past week, Trump’s legal team was thrust into disarray when his lead personal attorney John Dowd resigned under pressure, and it was announced that two new attorneys—Joseph diGenova and Victoria Toensing—would no longer be joining his team as planned. With Trump staring down the barrel of a sworn interview with Mueller, the president’s personal legal operation has largely been reduced to a one-man show in the form of Jay Sekulow, though former prosecutor Andrew Ekonomou will reportedly take on a bigger role going forward.