If the impeachment hearings this week are any guide, it will have to be the court of public opinion, not the court of the Senate, that removes President Donald Trump.

Increasingly, though, the pundits and commentariat are saying that Trump will be re-elected. If anything, that could be read as a good sign, seeing how many of them, including me, have got it so wrong in recent elections.

In the critical first full day of the impeachment hearings his week, the Senate voted along strict party lines in favour of Trump on important procedural points. Everything suggests that the party line will hold and Trump will be acquitted.

It will prove that campaign funds for Senators are more important than evidence. Bear in mind that this impeachment is not like the previous three where the President was somewhat entrapped by process and cover-up rather than doing something all on his own accord.

So will Trump be sworn in for a second term in a year’s time? Many people think that a sitting President routinely gets re-elected, but history shows otherwise. Almost a quarter have not been. And of those 10 who were not re-elected, six were Republicans, three were Democrats and one was from a time before the two parties existed.

For what it is worth, historian Allan Lichtman in “The Keys to the White House” developed 13 diagnostic questions to predict presidential elections. If six are false, the sitting President is predicted to lose the popular vote. Lichtman’s “keys” have been astonishingly accurate in the past. He predicted the Trump win, but thought he would get the popular vote, which he did not.

The 13 keys are electoral; economic; and foreign/military.

Against Trump are the taint of scandal and the mid-term loss. But on the other 11 he is looking good. He is incumbent. There was no serious contest for the party nomination. He passes the two economic tests. That the economic good news was caused at great environmental and fiscal cost does not matter.

He wins the charisma key, unless the Democrats get a better candidate than any of the present lot. Joe Biden is about as charismatic as his brown shoes. And Trump’s foreign and military policies, while a bit chaotic, are at least active. Also there has been no sustained social unrest.

However, there are nine moths to go. A foreign or military catastrophe is possible. So, too, is an economic downturn.

Lichtman puts no store in a lot of the usual tipster’s guides to re-election, especially polling data and advertising. He assumes, possibly correctly, that once the campaign is on voters dismiss much of the advertising as worthless spin.

It means, tellingly, that all those corporate donations amount to precious little in determining the result. But maybe that is not what they are for. The corporate donations are not made to influence the result of elections. That is why so many corporations donate to both sides. The donations are only made to influence, after the election, the actions of whoever happens to be elected.

On the Lichtman keys, Trump is headed for re-election. But there is a good case for saying that this time it is different. It is different because of Twitter.

Sure, other Presidents have spoken directly to the American people in televised addresses from the Oval Offie or in the Fireside Chats of President Roosevelt. But these direct appeals were choreographied and deliberated upon before they went out.

But with Trump, no other presidency has been so erratic. This is the first President who could Tweet his 150 characters of usually stream-of-consciousness jibberish directly to the American people without a second thought. No-one checks them for consistency or even legality, let alone taste or good sense.

That is rebounding. True, Lichtman says polls do not matter in the assessment of the re-electability of a President, but the latest CNN poll is perhaps different.

It says 70 per cent of voters are following the impeachment proceedings with great or moderate interest. And it says that 51 per cent of them think Trump should be removed from office.

Sure, polls to not go to everyone. Many people refuse to answer or are uncontactable. But those people are the sort of people who do not go out to vote anyway.

The poll suggests people are sick of Trump and his antics. You cannot fool a majority of the people for a whole term, even if his base remains doggedly attached.

It is here that the seventh of Lichtman’s 13 keys could prove crucial. It is policy change: The question is did the incumbent administration effect major changes in national policy.