No one should stress about whether Donald Trump has received or will receive all of his legal rights, or whether the triumph of his opponents is unfairly depriving him of the bully pulpit that his office has given him. Nor should they be concerned about the freedom of his speech. But they should be concerned about the effect of what he says, even when it involves lying, dissembling, or just plain hokum.

I would be only mildly concerned if he was hanged from the nearest tree, given his general enthusiasm for capital punishment. Arguments that his trial in the senate should go overboard to permit him to say what he wants swings on two points. First, he should not be allowed afterwards to be the martyr claiming that he was not heard in his defence. If his guilt is obvious, as his opponents (now even in his own party) claim, who needs a kangaroo court to convict him?

Second, his opponents hope and expect that Trump, at his show trial, will put his foot in it on many further occasions, making his guilt even more obvious. He has a long record of denying having said what the record shows him to have said, or of reconstructing his words and actions in impermissible ways, of outright lying, and of inventing distractions to avoid facing the truth. But he is not in power anymore. He has opponents in his own party who think he went too far. Many of whom want his continuing power and influence in the party destroyed. They do not want Trump back. Nor any member of his family.

A good many also want the process to further isolate other potential Trumps – such as Ted Cruz. They may not want to abjure populism or many of the myths it has perpetrated, but they now feel the need to distance themselves from the mob, mob hysteria and that ever-present threat of violence that Trumpism, like fascism in Italy, Spain, Portugal and Britain always involved.

An impeachment trial is an intrinsically political process. It may follow some of the forms of a criminal trial, indeed may have the Chief Justice playing chairman, but it is not a judicial process, and, for the most part, rulings and decisions cannot be appealed to the Supreme Court. If the Senate decides he is guilty (something which requires a two-thirds majority of the senate, or 67 votes) it does not amount to a conviction. For the first time in the impeachment of a president, Trump will be already out of office during the trial, so he cannot be deprived of his power, although the Senate may be able to strip him of continuing privileges.

If one is sticking to constitutional theory, no one should attach any particular legal significance to the verdict. It is not that greatly different or more serious than an Australian prime minister losing the confidence of his supporters. Given that the American senate is equally divided, a verdict finding the charge made out will show that he has completely lost the confidence of at least a third of his own party.

Most expect that a few Republicans, including the Senate Republican leader Mitch McConnell, believe that he incited an insurrection, but that the number of Republicans thinking that will fall short of the necessary 17. Many of the Republican senators will worry that their vote could cause a backlash back home, whether from the powerful Trump machine or from members of the partys lunatic fringe. Even McConnell, now trying to play the statesman has spent most of his recent career refusing to give an inch to the Democrats.

But it is not in the interests of the Democrats, whether in the congress or outside of it, to treat the senate trial as a mere political judgment, by politicians, of the deeds of the president. The impeachment charge alleges high crimes and misdemeanours. The team of people arguing the case in the senate from the house of representatives will be alleging distinct facts and interpretations of the law. There will be rulings on the admissibility of evidence, and procedure, by the chief justice.

Almost all of those involved will pretend that they are considering the evidence in a detached and fair-minded way. Even as they hold media conferences and otherwise engage in partisan leaking, they will affect a judicial manner. If a verdict after an impeachment trial is to have any political consequence, the Democrats must succeed in creating an impression that they have converted a political dispute into a form of legal judgment, representing a bipartisan consensus. Good luck with that. They want the public to accept the judgment, not as the resolution of a dispute between two of the three arms of government, but, in effect, as an independent judgment from the judicial arm.

Trump still owns and controls his party, and those who want it back will have to wrest it from him, and from the politicians, he has helped get elected.

This is difficult enough in an ordinary impeachment trial, if three previous cases, involving Andrew Johnson, Bill Clinton and Trump himself can be regarded as enough for a book of precedents. Trump himself can call evidence, and directly or through counsel comment on its significance. He can be echoed by his political supporters, who will be keen to portray his alleged sins as a mere political attack. With or without enough votes to prevent an adverse finding, their first objective will be to have Trumps supporters say that this is mere victors justice, pure spite rather than detached judgment, tainted by everything from crooked elections, fake evidence, and the socialistic, godless and generally abortion-mongering Democrats.

Defections, if any, by Republican senators will fit into a long-existing narrative about RINOs (Republicans in name only), many of whom will find their positions challenged at the next primaries. The Republican Party is as it is in part because the primary system, and Trump campaign funds, has tended to push candidates to the extreme rather than the centre. Trump still owns and controls his party, and those who want it back will have to wrest it from him, and from the politicians, he has helped get elected. The Democrats hardly have a role to play.

Ambitious Republicans will still see more advantage in identifying themselves with Trumpism (with or without Trump) than in being seen as collaborators with a discredited and corrupt system, and a party whose ideas and ideals they pretend to abhor most of all.

In the dream Democrat scenario, the impeachment trial sees an abashed and ashamed Trump, desperately trying to argue that his violent, abusive and threatening words were not egging on his lunatics. It involves Republicans who are embarrassed that it all came to this, somewhat sullenly agreeing that things must change and that the temperature needs to be lowered. Trump lawyers, perhaps, urging the equivalent of a plea of guilty with an explanation, in the hope that contrition will allow some reputation, some honour, perhaps a place in history to be salvaged from the wreckage. The Donald doesnt do contrition.

Much more likely is a perception by each of these players that the interests of Trump, his supporters in the party and in the community, and the hopes of any sort of restoration of Trumpism are in maximum non-cooperation, minimum contrition, and renewed efforts to claim it is all a conspiracy, not least by those who live in the swamp. The umpire it is appealing to is not the Senate or the new regime. It is the constituency. A constituency that is not much influenced by consensus in the mainstream media, or by facts. The war for hearts and minds will not be won by a manifesto or a book, let alone by an editorial in the New York Times.

Too often in the past, the response of the Democrats to losing their traditional base has been to reassure themselves that their logic and intentions have been good, and to seek out new constituencies so as to override its changed mood. The Democrats are right to sense that 21st century politics is about much more than the decline of the white working class. But they are wrong to ignore it and to address them in words that have lost meaning.