Andrew C. McCarthy provides pretty convincing evidence that the Obama Administration (and holdovers) wrongly use its law enforcement and counterintelligence powers to cripple Donald Trump, both as a candidate and later as president. I'll just quote the conclusion -- follow the link for a summary of the evidence.
The Obama administration and the FBI knew that it was they who were meddling in a presidential campaign -- using executive intelligence powers to monitor the president's political opposition. This, they also knew, would rightly be regarded as a scandalous abuse of power if it ever became public. There was no rational or good-faith evidentiary basis to believe that Trump was in a criminal conspiracy with the Kremlin or that he'd had any role in Russian intelligence's suspected hacking of Democratic Party email accounts.You didn't have to believe Trump was a savory man to know that. His top advisers were Flynn, a decorated combat veteran; Christie, a former U.S. attorney who vigorously investigated national-security cases; Rudy Giuliani, a legendary former U.S. attorney and New York City mayor who'd rallied the country against anti-American terrorism; and Jeff Sessions, a longtime U.S. senator with a strong national-defense track record. To believe Trump was unfit for the presidency on temperamental or policy grounds was a perfectly reasonable position for Obama officials to take -- though an irrelevant one, since it's up to the voters to decide who is suitable. But to claim to suspect that Trump was in a cyberespionage conspiracy with the Kremlin was inane . . . except as a subterfuge to conduct political spying, which Obama officials well knew was an abuse of power.
So they concealed it. They structured the investigation on the fiction that there was a principled distinction between Trump himself and the Trump campaign. In truth, the animating assumption of the probe was that Trump himself was acting on Russia's behalf, either willfully or under the duress of blackmail. By purporting to focus on the campaign, investigators had the fig leaf of deniability they needed to monitor the candidate.
You don't have to like or support Trump to be outraged by this illegal and immoral activity.