The vote taken Friday in the U.S. Senate was historic in an unwelcome way. It guaranteed that President Donald Trump's trial would be the first of 16 impeachment trials held in the Senate that would not include witnesses.

The outcome was not unexpected. Too many Republican senators were paralyzed from acting in good conscience by their fear of ugly repercussions from Trump supporters. But its certitude made it no less disgraceful.

Every Republican senator but two voted to block access to new information that would better explain Trump's actions in withholding military aid from Ukraine in exchange for that country pursuing investigations of a potential 2020 political foe, former Vice President Joe Biden, and Biden's son Hunter. The senators did this despite the publicly expressed willingness of former National Security Adviser John Bolton to testify.

Recent revelations in a manuscript written by Bolton make clear that he can provide invaluable information about Trump's Ukrainian campaign while also addressing one of the Republicans' major criticisms of the case presented by the House managers — a lack of witnesses with firsthand information about Trump's actions. And what Bolton knows is going to come out eventually, possibly making the senators who protected Trump look like fools and potentially sullying the inevitable acquittal of Trump.

Search for the truth

The frustration over witnesses rebounds to House Democrats, who never pursued a subpoena of Bolton because they didn't want to go through the lengthy court process that would have been necessary to obtain his testimony and were not certain of what the unpredictable Bolton was going to say.

We have no illusions that testimony from Bolton and other witnesses would have changed the outcome, which has been guaranteed from the moment the House voted to impeach Trump in December. But a trial is at its heart a search for the truth, and the Senate has now turned a blind eye to that pursuit. That is dispiriting. Not calling witnesses also strips any legitimacy from the process. Trump's inevitable claims of vindication will ring hollow.

Now the trial moves into its final phase. The postponement of the vote on Trump's guilt or innocence was due at least partly to the desire of many senators from both parties to have a chance to speak publicly on the Senate floor about the case and explain their decisions. Based on what some senators already have said, it's a welcome move. They should be heard, and on the record, explaining their moment in history.

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Lamar Alexander, a Republican from Tennessee, cast a pivotal vote against hearing witnesses, but not because he was trying to suppress information that would implicate Trump. Alexander said the House managers already had proved that the president did exactly what he was accused of doing and that his actions were wrong.

"It was inappropriate for the president to ask a foreign leader to investigate his political opponent and to withhold United States aid to encourage that investigation," Alexander concluded. "When elected officials inappropriately interfere with such investigations, it undermines the principle of equal justice under the law."

But Alexander argued that the proper remedy for that was the election in November, not impeachment. In making his case, Alexander, who surely was voicing the beliefs of some colleagues as well, might have inadvertently laid the groundwork for a vote to censure Trump, an appropriate action given the facts of the case.

Similarly, Lisa Murkowski (R-Alaska), another pivotal vote against witnesses, took both the House and Senate to task in justifying her decision. She rightly pointed out that the House impeachment process was "rushed and flawed," decried the obvious partisanship that marked every step of the process in both the House and Senate, and concluded with complete justification that "there will be no fair trial in the Senate."

End of trial

The trial will end in a few days. Its final stages will be jumbled with other high-profile political events — Monday's Democratic caucuses in Iowa and Trump's State of the Union speech scheduled for Tuesday night. The final vote should take place Wednesday.

But Trump's acquittal at that point will not mean an end to this ordeal. Investigations and revelations likely will continue. That's not a threat, but a recognition of the reality that what's been uncovered so far about Trump's conduct ensures more probes for more information.

What must be understood is that on Friday, the Senate abdicated its responsibility to the nation.

— The editorial board