In August last year two staffers from the US House Intelligence Committee arrived in London and turned up unannounced at the office of Christopher Steele. Not finding him there, they went to the office of his lawyer demanding to see him.

The timing of the visit was of importance. It took place when special counsel Robert Mueller and the Senate Intelligence Committee were making progress in their attempt to speak to the former MI6 officer who had produced the dossier on Donald Trump’s Russian connection. The two men had been sent by Republican members of the House Committee with the aim, it was suspected, of intimidating Mr Steele.

Last Friday, at the end of a week which had been dominated by highly damaging and humiliating revelations about Mr Trump in Michael Wolff’s book Fire and Fury, two Republican members of the Senate Judiciary Committee, Lindsay Graham and Chuck Grassley, asked the US Justice Department to start an investigation of Mr Steele over his contacts with the media. It is highly unlikely to come to anything, accompanied as it was with the acknowledgement that “it is not intended to be an allegation of a crime”.

But this is part of a far wider pattern of action to damage the investigations into the Trump team’s Russian connection, something which is only likely to gather more pace and scale after the announcement that preliminary discussions have already been held for the President to be interviewed by the FBI.

The attempt at undermining the inquiries had begun soon after they were announced, with Devin Nunes, the Republican chair of the House’s own inquiry into Russian meddling, being forced to step down over secret contacts with the Trump White House.

Mr Nunes, who refused to recuse himself temporarily from the chair and was subsequently cleared by the House Ethics Committee over the passing of information, has declared to Fox News that “I am in charge, I have always been in charge” of the investigation. Mr Nunes, it is believed, was one of those who sent the staffers to see Mr Steele last summer without telling the Democrats in the committee.

Mr Nunes has been pursuing alleged bias against Mr Trump in the Justice Department and FBI, issuing subpoenas for confidential documents in the Russia inquiry. Mr Nunes has charged that “it seems the Department of Justice and FBI need to be investigating themselves. The senior Democrat in the House Committee, Adam Schiff, has complained “from the beginning of this investigation there’s been an effort to circle the wagons around the White House by the chairman and some of the President’s allies”. Mr Nunes, he held, wants to investigate “anyone but the Russians”.

A whole range of FBI and Justice Department officials, from Robert Mueller and acting FBI Director Christopher Wray to deputy attorney general Rod Rosenstein, who has been vocally supportive of Mr Mueller, have come under attack from the Republican right.

Some of the focus is now on Jeff Sessions. The attorney general recused himself from the Russia investigation after revelations of a meeting he had with the Russian ambassador to the US in 2016. Mr Trump is reported to have been furious with Mr Sessions and had asked White House counsel Don McGahn to urge him to change his mind.

Mr Trump has repeatedly railed against Mr Rosenstein. Even last July he was annoyed that “Rosenstein is from Baltimore: there are very few Republicans from Baltimore, if any, he is a Democrat”. Mr Rosenstein, it has been pointed out, is neither from Baltimore nor a Democrat. But Mr Trump continues to see him as a threat.

Soon after the news broke of Mr Trump’s projected interviews with investigators, messages began to appear in social media from the President’s supporters of the need for changes in the Justice Department. Tom Fitton, the head of a conservative lobbying group called Judicial Watch, tweeted: “Sessions should unrecuse himself and clean house.” Republican congressmen Mark Meadows and Jim Jordan have demanded recently that Mr Sessions should resign.

The removal of Mr Sessions, Trump supporters have pointed out, would enable the appointment of a new attorney general who could take back the Mueller investigation from Mr Rosenstein, then give it a time limit and start cutting back on funding with the hope it will peter out.