The Mueller investigation shows us that Donald Trump is still beatable by politics, if not by law

The investigation turned out to be less damaging to him than Trump feared. His initial reaction, however, shows he is vulnerable, just like any other politician

The most telling line in Robert Mueller’s report was its account of how the president reacted when he heard the independent counsel had been appointed to investigate him: “Oh my God. This is terrible. This is the end of my presidency.”

In that private moment, we see Donald Trump without the bluster, behaving surprisingly like a normal politician. For all that he is usually portrayed as a deliberate disrespecter of rules – and therefore powerful – here he was, vulnerable, upset and self-pitying.

This is a familiar theme in memoirs and biographies of political leaders: a tendency to exaggerate threats to their position and to dramatise any setback as the end of their time at the top.

Trump realised that an investigation into his collusion with Russian interference in the 2016 election was a threat to him, although in the next breath he seems to have more accurately assessed that it was a constraint rather than a terminal blow: “Everyone tells me if you get one of these independent counsels it ruins your presidency. It takes years and years and I won’t be able to do anything.”

Again, this is the sort of thing you would expect a “normal” president to say. It sounds like Richard Nixon or Bill Clinton, including the next sentence, the wail of the child within: “This is the worst thing that ever happened to me.”

In fact, the investigation turned out to be less damaging to him than he feared. It did distract him and his administration from other things, and he still hasn’t built that wall, but although he was specifically not exonerated neither was he found guilty.

As ever it was the cover-up rather than the original wrongdoing that was most dangerous to him. Mueller found plenty of evidence that Trump had wanted to obstruct justice but none that he had actually done so.

In part this was because his report confirmed what Michael Wolff had described in his book Fire and Fury – a president frustrated by the refusal of his underlings to do as told. At the time of Wolff’s book last year, there was some muttering on the fringes of the paranoid right about evidence of the “deep state” working against an insurgent who was a threat to its power.

But the Mueller report makes it clear that most of the people who refused to carry out Trump’s instructions were his own appointees. They recognised when they were being asked to cross an ethical line and refused – or, less actively, simply did nothing.

In the end, however, Mueller failed to find compelling evidence that the president had obstructed justice. Mueller was never likely to do so and, even if he had, the political process of impeachment and conviction would never have resulted in Trump’s removal from office. At worst he would, like Clinton, have been impeached by the House of Representatives and acquitted by the Senate.

That ought to be the lesson for Trump’s opponents: that he needs to be defeated by politics rather than by law. He was beatable in 2016, and the hoo-ha about Russian interference – which was mostly trivial – has been magnified because Hillary Clinton was such a poor candidate.

The Mueller report confirms that Trump is beatable next year. He is not the all-powerful monster of the liberal imagination. He is just another vulnerable politician who had some good lines on TV and social media last time. A charismatic Democrat who could energise the better instincts of middle America should trounce him.