Well, when Bill Clinton faced an impeachment those who were completely supportive of him as a president also became more and more enthusiastic to support him (of course that entire affair was one big joke). Although it did not lead to the Democrats giving the next president after Clinton's 2nd term ended, but every one I spoke agreed to it that if Bill Clinton was allowed a 3rd term he would have won the elections easily, and that impeachment would certainly have played a role in it. Of course, this was in the Democrat's favor, but I'm sure they don't want to repeat the Republican's mistake. Of course in Clinton's case it was a ridiculous case of having sex with a female working in his office, in Trump's case the parallels with the Watergate affair are uncanny, but since we all know that the Trump fans will never admit Trump to be guilty even if all evidence is irrefutable, this will indeed solidify his 2020 election campaign. Although this can lead to Trump getting away with things that are crimes or at least not the way they should be (as a lot is still vague on this point), it's clear that the Democrats cannot risk this. Even it Trump's impeachment is successful, it won't be completed before the elections, and until then he can still run for his second term and if he wins it, we have a Republican in the office for another 4 years for certain, because Trump would then just be succeeded by another Republican. In any case, the Republicans can win a lot by an impeachment. And I suppose the Achilles heel of democracy has now been painfully revealed.