We need only one witness at impeachment trial

Then-national security adviser John Bolton adjusts his glasses before an interview at the White House in Washington on March 5, 2019. Credit: AP/Jacquelyn Martin
The credible reports that former National Security Adviser John Bolton has first-hand knowledge that President Donald Trump sought to withhold aid to Ukraine in return for an investigation into former Vice President Joe Biden and son Hunter, should spur Democrats to stop asking for multiple witnesses to appear at the Senate impeachment trial.
Democrats now have Bolton, a very good witness with an upcoming book that would spell out Trump's misdeed. All that is required is Bolton, who reportedly complained to Attorney General William Barr that Trump was cozying up with dictators. And because Bolton has flirted with testifying before the Senate trial, his appearance would stand as definitive testimony.
Otherwise, the Senate trial will continue to be a kangaroo court and the world will see it for what it is: an unambiguous demonstration by the Republican-controlled Senate of incompetence, devoid of moral integrity. Let Americans watch as the Senate pursues the kind of trial that goes against everything our nation stands for: the rule of law and justice.
Why even attempt to introduce good people into a bad process? Foreign service officers, civil servants, ambassadors and White House experts already testified before the House Intelligence Committee and have paid a high price for their honesty. There is little to be gained by dragging them through this trial in a circus-like atmosphere. Bolton would be a new face for much of the public and his testimony likely would go beyond Ukraine and potentially would underscore other bad dealings the president allegedly conducted with China and Turkey.
In the fact-averse world created by Trump, there is no room for ambiguity. Things are black or white; the notion of something gray is unacceptable to many congressional conservatives who refuse to respect facts and witnesses, anyway. Why bother to use too many messengers and risk having the Senate call the Bidens, who don't appear to have done anything untoward?
Let Bolton do the heavy lifting now.
Tara D. Sonenshine, a former U.S. undersecretary of state in the Obama administration, advises students at The George Washington University.