In writing my Observer column this week I had to check something about the Watergate episode – in which a sitting US President was forced to resign after the Washington Post revealed that a slush fund that had been used to finance the Watergate burglars (among many other sleazy operators) had been run from the White House by HR Haldeman, Richard Nixon’s most senior aide.

Those activities (according to the Wikipedia summary) included such dirty tricks as bugging the offices of political opponents and people of whom Nixon or his officials were suspicious. Nixon and his close aides also ordered investigations of activist groups and political figures, using the Federal Bureau of Investigation (FBI), the Central Intelligence Agency (CIA), and the Internal Revenue Service (IRS) as political weapons.

The scandal led to the discovery of multiple abuses of power by members of the Nixon administration, the commencement of an impeachment process against the president, and Nixon’s resignation in August 1974. The scandal also resulted in the indictment of 69 people, with trials or pleas resulting in 48 being found guilty, many of whom were top Nixon officials.

Having been catapulted back into that period, I then re-watched one of my favourite movies, All the President’s Men, which I haven’t seen for years. It tells the story of how two junior reporters – Carl Bernstein (played by Dustin Hoffman) and Bob Woodward (Robert Redford) – traced the money given to the burglars to the inner sanctums of the White House. It’s a great, romantic story about journalism at its best, and so very comforting to those of us who believe in our trade.

But then an uncomfortable thought struck me. The Watergate story is reassuring because it shows how a democracy should work. The journalism produced evidence of a dangerous high-level conspiracy – a conspiracy which was of course energetically denied by all those involved in it. But once the journalists had done their work, the action passed to Congress – which in turn did its job, by launching an impeachment process against the sitting president. Nixon resigned before that process could run its course.

Like I say, this is how the system ought to work. But then consider the difference between then and now. One lesson from the Mueller Report is that no amount of evidence that Trump had – for example – colluded with the Russians would have prompted a dysfunctional, partisan, Republican-dominated Congress to launch an impeachment process. And although the Democrats are now in charge of the House of Representatives (and therefore of impeachment) it’s hard to see them making any real progress before 2020, when it’s likely (IMHO) Trump will have been re-elected.

Which of course makes one wonder what kind of crime this president would have to commit before Congress would act? It all reminds me of something he said during the 2016 Election campaign: “I could stand in the middle of 5th Avenue and shoot somebody and I wouldn’t lose voters.”

I gloomily suspect that that judgement was accurate. It doesn’t seem to matter what he does: his ‘base’ of 30% seems unaffected.