When Potus first took office, (((they))) tried everything to change public opinion enough to justify impeachment. They needed to get the public on their side and threw everything they had at the wall to try and get his approval ratings low enough. If they had anything, anything at all, they would have used it. Even the most ridiculous speculation was fodder. Yet, they had nothing. In fact, they had to spend millions to fabricate a massive Russiagate conspiracy to try and take him down.
To try and assert they have dirt but withheld it for some unknown reason is not very logical. Agreed, no one is perfect, but if he had in his mind from decades ago to one day run for President, then likely he kept his nose clean, for the most part. Making human mistakes is one thing. Committing crimes is something totallly different.