We'll never see the truth come out, because both parties don't want it to, but he and Biden and those in his inner circle conspired against Trump, particularly during the transition to Trump. Hillary had already laid the groundwork for the noise to cover it up when she brought up the phony Russian collusion narrative during the debates.
Remember when Trump tweeted that he had been "wire tapped" at Trump tower? The media and most liberal talking heads went bananas claiming Trump was bananas. Turned out Trump was right. He was usually right when he made these claims, because he had the intel reports. It's just that he never had the DC swamp on his side (do we even have to wonder why about that...) for it all to come out. Imagine if Trump had an AG who actually cared about the integrity of the DOJ? Whoa...
I'm not necessarily saying president Obama should be retroactively impeached (although thanks to the idiots in the current Democrat party, the bar *has* been lowered), but I am saying that all presidents of both parties have done things that, were the facts shown in the light of day, would be impeachment worthy. Those who think there's no swamp that wants to protect itself, are pretty naive in my opinion.