PERHAPS the only reason to doubt Donald Trump is contemplating sacking his attorney-general, Jeff Sessions, in order to protect himself and his associates from the counter-espionage investigation being run by Robert Mueller, is that the president has been so astonishingly upfront about it. On July 25th he tweeted that the attorney-general, one of his earliest and most influential supporters, was “VERY weak”. Asked whether he intended to sack him, he replied: “Time will tell.” Yet Mr Trump’s history of rule-breaking suggested he was indeed weighing a measure that would pitch his scandal-plagued presidency into its biggest crisis yet.

Mr Trump said he was angry with Mr Sessions because he had recused himself from an FBI investigation into Russia’s efforts to fix the election in Mr Trump’s favour, with possible assistance from members of the Trump campaign team. Mr Sessions announced that decision in March, after it was revealed that he had withheld details of meetings with a Russian diplomat, Sergey Kislyak, during his Senate confirmation hearings.

The indirect cost to Mr Trump of Mr Sessions’s recusal is that the FBI probe has now been passed to an independent counsel, Mr Mueller, a former FBI director with a reputation for probity and rigour earned under both Republican and Democratic administrations. His investigation, which is more public and high-powered than the FBI’s, was launched by Mr Sessions’s deputy, Rod Rosenstein, after Mr Trump fired James Comey as FBI director in May. According to Mr Comey, he was axed after he denied a request from the president to drop part of his investigation—into another arch-Trump supporter, Michael Flynn.

It seems unlikely that Mr Sessions, had he not recused himself, would have launched the independent probe into Russia and the Trump campaign; as the first senator to endorse Mr Trump, he played a lead role in that campaign. Given that Mr Mueller was hired over two months ago, it is also reasonable to assume that the president’s problem with Mr Sessions does not really concern the fact that he let the probe happen so much as that, because of his recusal, he cannot end it.

Unlike the more powerful office of the independent counsel, which was scrapped in 1999 after plaguing the presidency of Bill Clinton, a special counsel can be sacked, for due cause, by the attorney-general (or, in the current situation, by Mr Rosenstein). The president, as head of the executive branch, can legitimately demand such a step, provided he also identifies due cause. And there is little doubt that the president wants to see the back of Mr Mueller, who is reported to have begun investigating Mr Trump’s financial affairs. The president has suggested some members of the counsel’s team of a dozen top-notch investigators are “conflicted”, perhaps because of past donations to Democrats (though Mr Trump was once a donor to them too).

Mr Trump and his family are also feeling the heat from three congressional inquiries, after revelations that the president’s eldest son, Donald Trump junior, son-in-law Jared Kushner and then campaign boss, Paul Manafort, met a party of Russians during the campaign to discuss possible dirt on his Democratic rival, Hillary Clinton. Mr Kushner was interviewed about the meeting, behind closed doors, by the Senate intelligence committee on July 24th and the House intelligence committee the next day. In a pre-released statement, he denied having colluded with any foreign power. Mr Manafort, who is separately reported to have owed pro-Russia Ukrainians $17m shortly before he was hired by Mr Trump, testified in private to the Senate intelligence committee. Both he and Donald junior are expected to appear before the judiciary commitee.

After a slow start, there are signs that all three congressional committees are starting to take their investigations seriously. They are unlikely to reach any conclusion before Mr Mueller does. Yet as Congress represents by far the most important potential check on Mr Trump’s rule, the president will understand that sacking Mr Mueller, after first sacking Mr Sessions, would spark a backlash. How seriously he is contemplating it must therefore depend on how worried he is about what Mr Mueller might find.