By Steven V. Roberts

As election year 2020 approaches, there’s one thing that American voters need above all: more information, more facts and more insight into how the president thinks and acts, in public and in private.

That information cannot just be filtered through the conservative echo chamber that slavishly supports the president and slants every report in his favor. It has to come from independent, professional sources untainted by partisanship — judges and journalists, investigators and prosecutors. As U.S. District Judge Amy Berman Jackson put it: “If people don’t have the facts, democracy doesn’t work.”

Those facts also have to come from the president’s top aides, questioned under oath and held accountable for the truthfulness of their answers.

The public — in a rare burst of consensus — broadly agrees. In the latest ABC/Washington Post poll, 71% say the president should allow his aides to testify during the Senate impeachment trial in January.

That includes 2 out of 3 Republicans and 7 out of 10 independents.

A new Fox News poll reinforces that demand for openness, with only 36% saying the president has been “cooperating enough” with the impeachment inquiry, while 52% say he’s been stonewalling.

Mitch McConnell, the Senate Republican leader, opposes calling witnesses, but Chuck Schumer, his Democratic rival, is pressing him hard. “Why is the leader, why is the president, so afraid of having these witnesses come testify?” Schumer asked on the Senate floor. “Senators who oppose this plan will have to explain why less evidence is better than more evidence.”

We know the ending for the movie called “Impeachment.” The Republican-controlled Senate will vote to exonerate the president early next year. But “Impeachment: The Sequel” won’t be out until November, and that ending has yet to be written. Voters, not senators, get the final say about this president, and they cannot make that judgment fairly without all the facts about Trump’s performance in and out of office.

Full disclosure, of course, is the last thing the president wants. He’s done everything possible to thwart the House investigation: blocking Democrats from questioning his aides and obtaining key documents. One article of impeachment accuses Trump of showing “unprecedented, categorical and indiscriminate defiance” in the face of numerous legal subpoenas.

But his defiance doesn’t end with concealing information. As a New York Times editorial put it, Trump and his allies “have spread toxic misinformation and conspiracy theories to try to justify his actions.”

Virtually every day, Trump does something to pollute the information environment and undermine sources that contradict his warped worldview. When impressive impartial diplomats testified about his campaign to pressure Ukrainian leaders, he dismissed them as “human scum.”

When a Fox News poll showed 54% of Americans favoring impeachment, Trump told Fox to fire their pollster.

Law professor Jonathan Turley made a good point that the Democrats were rushing too fast toward impeachment. As he told a House hearing, “You have to give the time to build a record.” But that record isn’t just relevant to impeachment; it’s relevant to the election, as well. So even if Senate Republicans eventually clear the president, they have an obligation to call witnesses and inform voters as completely as possible about Trump’s actions.

There’s little reason for optimism about this. The Republican Party is a wholly owned subsidiary of Trump Enterprises, and won’t do anything to jeopardize the president’s reelection chances. But fortunately, there’s another arena for fact-finding and record-building — another branch of government that is not completely controlled by Trump: the federal courts.

Three different cases demanding information from the president have now been accepted by the Supreme Court for argument next spring. The first case, filed by Manhattan district attorney Cyrus R. Vance Jr., demands financial records from Trump’s accounting firm, Mazars USA.

Vance argued that the controlling precedent was set during Watergate, when the Supreme Court voted unanimously to force President Nixon to hand over White House tapes that eventually proved his guilt. The same precedent has been invoked in the two other cases, which involve House committees run by Democrats seeking financial records from both Mazars and Trump’s bankers, Deutsche Bank and Capital One.

Trump is counting on the High Court’s five-member conservative block to protect him. But the precedent is clear, and so is the national interest. The justices — in the name of a healthy and functional democracy — should rule against the president and force him to reveal facts voters deserve to know before they decide to give him a second term.

Steven Roberts teaches politics and journalism at George Washington University. He can be contacted by email at stevecokie@gmail.com.