In some ways the Republicans know they did wrong, but felt helpless to do anything about it. Many admitted that indeed the charges had been proved. In some cases they felt what Trump did was bad, it just wasn't bad enough to upset the status quo. Others were aware that they could protest (at some harm to themselves) and in the end the result of acquittal would prevail.
The stubborn base feels they have been treated unfairly. Why are they poor and powerless while obviously selfish people hurt them? Many of them are essentially one issue voters who feel very strongly about their concern and overlook how Trump (and the Republicans) have packaged their concern together with economic concerns of the rich. (http://www.therealjohndavidson.com/2020/01/one-issue-voters.html) Trump is a vocal liar who has achieved celebrity status. He uncovers prejudice that many are reluctant to admit.
The electoral system was set up by slave owners who feared the industrial north would outvote them and curtail their economic system. Slavery has been abolished, but there has been a long legacy of pride and prejudice that is still part of human nature. In Canada to lure Prince Edward Island into Confederation they were offered and accepted a guarantee of 4 members of Parliament that was disproportionate to their population. In America small states are able to fight above their weight class and to some extent it can be justified. They have a different legitimate viewpoint that should be heeded. But sharp politicians realize they don't need to cultivate a majority vote, but with a winner take all in most states can squeeze a winning combination. Opinions are so set that presidential candidates do not waste precious resources in states that are consistently on one side or another.
The media often is quite strong in their condemnation of Trump and his policies, but it seems tempered. He is so controversial that he draws attention and thereby gains a relatively cheap platform and it seems to reinforce his celebrity status. Wealthy interests are increasingly in control of media outlets and in some cases are very slanted and in others soften their criticism. They are increasingly sophisticated how to manipulate using massive amounts of data.
One of the problems of unregulated capitalism is that it tends to concentrate wealth. The wealthy have power that they naturally tend to use in order to maintain their wealth. They are the ones who pay for lobbyists to persuade those with legislative power to pass laws that favor the rich. Taxes are one area that can be modified so the rich can grab a larger share of profits. Regulations are a restraint on their ability to squeeze more profit. Unions and minimum wage laws impact their ability to boost profits. Discrimination laws impact working conditions and in many cases affect their feelings of self righteous superiority. Health regulations affect what we eat, drugs we use and how safe we are. Trump is especially vain and selfish and favors his personal and family interests above all others. Campaign laws have loosened so that the very wealthy can get their message out and to some extent without attribution. Corruption has now reached the stage where a dishonest politician can gain help from foreign entities who have their own agenda.
He may not be acquitted in the next few days as predicted, but it certainly seems likely. The Democrats are in the midst of selecting a candidate to oppose Trump and have to be concerned how this impeachment effort affects their choice. One of the biggest single factors is the ability to defeat Trump. Joe Biden may be tainted, but others feel he is the one most likely to defeat Trump. It is certain whoever wins the nomination will be slandered viciously by the Trump team. Other Democrats feel that Trump can be defeated by any candidate, so why not go for a more progressive candidate.
To me where Trump is more vulnerable is his base. They have been lied to and in many cases hurt badly. All the talk about stock market records and job reports hides many economic realities. Wealth is being more concentrated, Americans are not protected as much as before and important problems such as the climate crisis are being ignored.
Bolton's book, at this point seems like it could make a difference. An unlikely Democrat tool he has his own motivations and policy preferences. Although it supposedly contains some explosive information with the credibility of a true insider. There have been other incriminating books that have probably dampened Trump's approval, but have had almost no effect on his base. He has proved most of the time that he can use his base to gain his preferences.
Part of me is outraged at the many insults he has delivered and the harmful policies he has helped arrange. To others they are amusing or helpful or ignorable. Not enough impact. It is sometimes difficult to convince someone they have been lied to or worse, manipulated, but that may be the most effective. If they are really upset about abortions they can easily forgive infidelity or a tax break for the rich. They accept that Trump exaggerates, embellishes, distorts and outright lies. Some rationalize that he does something really important to them or is entertaining.
The hope is he will lie about something that is important to them and they become aware of it. What is important aside from the one issue? One possibility is betrayal of the nation, not just accepting help. There have been lots of examples---ignoring his own intelligence agencies and accepting the word of Putin--abandoning the Kurds who were essential to U.S. policy, delaying much needed aid for the Ukrainians to resist the Russians, poor treatment of immigrants who have helped America. It won't affect some, but if really hammered home which maybe Bolton's book may help with it will affect some.
Everyone has friends, acquaintances, fellow workers who have been betrayed by Trump who proclaims otherwise. Parents, children, siblings have been hurt through de-regulations, or abusive powers. It is easier to ignore the abuse of immigrants even if that issue is not your core issue. Some will come to realize they have been bought so that others (including some they care about) can suffer.
Sincerity is a key component to acceptance. Trump does many things to undercut his sincerity. His infidelities should shock more people. His coverups are also an indication of his deception.
What he really thinks of his base which is not as amusing as his usual insults. He loves the poorly educated. He knows better than the Generals. He is undermining health care. He is doing away with protections to favor big business.
It is true that the Democrat policies (pretty much any of the candidates) are superior in my opinion than what Trump is actually doing. They also are tainted with wealthy money trying to influence the country, but their policies are directed at actually helping the majority. They should argue for their policies and offer contrasts. That may not do it. Much as I admire Michelle Obama, especially when she said "when they go low we go high" it is time to draw the contrasts in more than just style.