Americans want a fair impeachment trial. Senators can make that happen. Despite Donald Trump's stonewalling, Ukraine evidence keeps emerging, crying out for Senate to call witnesses and uncover hidden documents: Our view

The Editorial Board | USA TODAY

Show Caption Hide Caption Presidential impeachment: Clinton, Johnson, Nixon test U.S. democracy Presidents have been impeached, but none have been removed from office due to impeachment. Confusing? Here's how.

When Chief Justice John Roberts swears in all 100 senators as jurors for the impeachment trial of Donald John Trump, each will promise to "do impartial justice according to the Constitution and laws."

But the Founders were clear eyed and prescient about the political realities of judging a president. "The greatest danger (is) that the decision will be regulated more by the comparative strength of parties than by the real demonstrations of innocence or guilt," Alexander Hamilton wrote of the impeachment process in Federalist No. 65.

That certainly appears to be the case as the Trump impeachment, just the third such trial in U.S. history, shifts from the Democratic-controlled House to the Senate, where Republicans hold a 53-47 majority. With 67 votes needed to remove Trump from office, his acquittal seems assured.

6 in 10 expect a fair Senate trial

Even so, 62% of Americans polled recently expressed the hope that a fair trial is possible.

To their credit this week, senators rebuffed pressure from Trump and his allies to short-circuit the proceedings. Trump twice tweeted that the Senate should simply dismiss the "Impeachment Hoax" short of trial. To do otherwise, he argued, would give credence to the allegations against him.

TEA PARTY PATRIOTS CO-FOUNDER: Impeachment inquiry is a sham

But Senate Republican leaders, recognizing that outright dismissal would risk fierce blowback against some GOP candidates, promised full airing of House articles that Trump abused his power trying to extort political favors from Ukraine and then obstructed Congress' investigation.

What should such an airing look like? To an American public familiar with courtroom dramas, a search for truth involves evidence, documents and relevant witnesses.

Yet Senate Majority Leader Mitch McConnell — who promised Fox News last month that "there will be no difference between the president's position and our position" on running a trial — has mocked the notion of calling new witnesses.

"Nothing in our history or our Constitution ... insist that the Senate fill in the blanks," he said from the Senate floor Tuesday.

Blocking testimony and documents

McConnell didn't mention the reason those blanks exist: White House stonewalling that blocked the testimony of key aides and release of key documents. Sooner or later, truth tends to seep out. In this case, it turned out to be sooner. Just since the House voted Dec. 18 to impeach Trump:

►Highly redacted emails — obtained through the Freedom of Information Act by the Center for Public Integrity and released Dec. 20 — provided further proof of White House efforts to hide the suspension of nearly $400 million in military aid to Ukraine, the leverage Trump was using to extort political favors from Kyiv.

►Just Security, an online analysis forum, reported Jan. 2 that other government emails showed concerns by the Pentagon about the legality of withholding that crucial military aid to Ukraine.

►Former national security adviser John Bolton, who has direct knowledge of Trump's actions and conversations regarding Ukraine, said Jan. 6 that he'd testify in an impeachment trial if subpoenaed.

►On Monday, a California cybersecurity firm announced that in November, Russia successfully hacked the Ukrainian gas company that employed Democratic candidate Joe Biden's son, Hunter, and is at the heart of the impeachment inquiry.

►Further evidence of Trump's efforts to pressure Ukraine to announce an investigation of the Bidens surfaced Tuesday, when House committees released documents provided by Lev Parnas, who is facing a federal indictment and is an associate of Trump's personal lawyer, Rudy Giuliani.

With a simple majority of 51 votes, senators can summon witnesses like Bolton or Parnas, or demand previously denied government communications bearing on impeachment. Just four of the 53 Republicans would have to agree to join the Democrats to make that happen.

It would go a long way toward reassuring the American people that the process isn't rigged, even if the outcome appears preordained.

USA TODAY's editorial opinions are decided by its Editorial Board, separate from the news staff. Most editorials are coupled with an opposing view — a unique USA TODAY feature.

To read more editorials, go to the Opinion front page or sign up for the daily Opinion email newsletter. To respond to this editorial, submit a comment to letters@usatoday.com.

If you can't see this reader poll, please refresh your page.