Today, the Senate of the United States of America is expected to decide whether to hear witnesses before rendering a verdict on impeachment charges against the nation’s president.

It’s unconscionable that senators would even consider proceeding without testimony from those who had direct contact with President Donald Trump about withholding aid to Ukraine. Senate Republicans are running roughshod over this nation’s basic notions of a fair trial — fair not just for the president but also for the country.

Republicans say that those witnesses should have testified at the House impeachment hearings — which, of course, ignores that Trump, unlike President Clinton when he was facing an impeachment trial, actively, and successfully, worked to block testimony. That’s why Trump faces the second article of impeachment, obstruction of Congress.

The outcome of the Senate trial is not in doubt. With a two-thirds vote needed to convict and Republicans holding a majority, Trump will not be removed from office. And, without witnesses, pursuit of the truth will be suppressed in the process.

The nation remains evenly divided over whether Trump should be re-elected and whether the Senate should remove him from office. But about two-thirds support calling witnesses. In other words, regardless of whether they think there’s enough evidence for conviction, most line up behind a fair process.

They understand that hearing from witnesses is fundamental to our notion of justice, which is core to who we are as a nation. The Founding Fathers wisely created a government where a president’s power is checked by Congress. A Senate trial without witnesses weakens that system by abdicating the responsibility to pursue facts and hold the executive branch accountable.

The reasoning of Trump’s lawyers, and many of the Republican senators, in their efforts to block testimony is frightening. You don’t need witnesses, they effectively argue, because, even if everything alleged is true, no impeachable offense could have been committed.

In other words, it’s OK for an American president to reach out to a foreign nation for personal political support in exchange for U.S. public money. Alan Dershowitz, the constitutional scholar on Trump’s legal team, took it to an absurd level this week.

“Every public official I know believes that his election is in the public interest,” he said. “… If the president does something which he believes will help him get elected, in the public interest, that cannot be the kind of quid pro quo that results in impeachment.”

That’s the sort of reasoning we would expect in a totalitarian or authoritarian nation — like Russia — not in our constitutional democracy. The message to a narcissist like Trump is he is free to do whatever he wants because his decisions, whatever they might be, are in the public interest. And don’t worry about what witnesses might say; they’re irrelevant.

If the Senate moves forward today without witnesses, the Senate trial will be a sham. It will be sad day for our democracy and our country if our elected leaders willfully abandon their constitutional responsibilities.