“Poor Richard M. Nixon was almost certain to be impeached, and removed from office, after the infamous ‘smoking gun’ tape came out. On that tape, the president is heard directing his chief of staff to get the CIA director, Richard Helms, to tell the FBI ‘don’t go any further into this case’ — Watergate — for national security reasons. That order never went anywhere, because Helms ignored it.

“Other than that, Nixon was mostly passive — at least compared with Trump. For the most part, the Watergate tapes showed that Nixon had ‘acquiesced in the cover-up’ after the fact. Nixon had no advance knowledge of the break-in. His aides were the driving force behind the obstruction.

“Trump, on the other hand, was a one-man show. His aides tried to stop him, according to Mueller: ‘The President’s efforts to influence the investigation were mostly unsuccessful, but that is largely because the persons who surrounded the President declined to carry out orders or accede to his requests.’

“The investigation that Trump tried to interfere with here, to protect his own personal interests, was in significant part an investigation of how a hostile foreign power interfered with our democracy. If that’s not putting personal interests above a presidential duty to the nation, nothing is.

“White House counsel John Dean famously told Nixon that there was a cancer within the presidency and that it was growing. What the Mueller report disturbingly shows, with crystal clarity, is that today there is a cancer in the presidency: President Donald J. Trump.

“Congress now bears the solemn constitutional duty to excise that cancer without delay.” — from “Trump is a cancer on the presidency. Congress should remove him,” a 4.18 Washington Post op-ed by George Conway.