Here's what you need to know on subjects likely to be heard in the impeachment hearing.
Donald Trump has been fulminating for weeks over the impeachment inquiry, which he sees as a persecution cooked up by Democrats and "Never Trumpers."
In reality, a collection of witnesses that includes Still Trumpers, Once Trumpers and the apolitical civil service has put together a largely cohesive account of a president exerting pressure on a foreign power for political benefit at home.
On Wednesday, with the opening of historic public hearings, Republicans in the House are primed to defend him while Democrats lean in to make their points before a presumably big TV audience.
Here's a guide to separating fact from fiction on subjects likely to be heard in the hearings:
Republicans seem disinclined to echo Trump's description of his July 25 phone call with Ukrainian President Volodymyr Zelensky as "perfect." But they do suggest it was harmless.
A Republican staff memo, laying out talking points for the hearings, asserts that the rough transcript of the call "shows no conditionality or evidence of pressure."
In fact, Trump clearly exerted pressure in the phone call. As well, he made his request for a Ukrainian investigation of Democrats right after Zelensky raised the subject of U.S. military assistance.
When Zelensky told him Ukraine was "almost ready" to buy more anti-tank missiles from the U.S., Trump responded: "I would like you to do us a favor, though."
Trump did not state explicitly that he would hold back military aid or benefits to Ukraine unless he got what he wanted.
But he repeatedly stated that both his attorney general and personal lawyer would follow up with phone calls about the investigation he was seeking, and "we will get to the bottom of it."
Moreover, Trump's people were engaged in a systematic effort behind the scenes for months to get Ukraine to probe Joe and Hunter Biden and other Democrats. According to closed-door testimony, U.S. military aid was not to be resumed until Ukraine made a public statement committing to an investigation.
THE 'RABBIT HOLE'
Trump's statements about Ukraine rest on two arguments, which House Republicans are echoing to varying degrees despite scant evidence behind the allegations.
One is that Joe Biden used the vice presidency to protect his son Hunter, who was doing business in that country. The other is that Ukraine colluded with Democrats to the disadvantage of the 2016 Trump campaign.
The first argument has this much going for it: Hunter Biden's position on the board of a Ukrainian energy company, while his father was serving as an emissary to that country, looked bad. Yet no wrongdoing by either Biden has been substantiated.
The second argument hangs on a fevered conspiracy theory that even some Trump officials have tried to bat away.
Trump's first homeland security adviser, Tom Bossert, said Trump was told by his staff that the theory was "completely debunked" well before the Trump pressed Ukraine to investigate it.
The theory resurfaced from GOP lawmakers in the closed impeachment hearings, exasperating Fiona Hill, an intelligence official from the Bush and Obama administrations who served as special assistant to Trump on the National Security Council until she resigned in the summer.
"It is a fiction that the Ukrainian government was launching an effort to upend our election," Hill testified. "I'm extremely concerned that this is a rabbit hole that we're all going to go down in between now and the 2020 election, and it will be to all of our detriment."
A RIGHT TO DUE PROCESS
It's been a familiar refrain from Republicans throughout the impeachment inquiry: The proceedings are an illegal "sham" and a "coup," and Trump has a right to confront his main accuser, an anonymous whistleblower.
"Fake Hearing (trial) in the House, as they interview Never Trumpers and others, I get NO LAWYER & NO DUE PROCESS," Trump tweeted recently.
Trump is off the mark.
The House is conducting a hearing, not a trial, so no constitutional rights are being violated here.
Nor is there any illegal takeover afoot —the impeachment process is unfolding as outlined in the Constitution, which gives the House the sole power to impeach and the Senate the sole power to remove a president from office.
Trump is correct that he and his legal team are excluded from the public hearings beginning Wednesday, but he hasn't been charged with anything and has no constitutional right to be represented by a lawyer in this proceeding.
The hearings led by the House Intelligence Committee are akin to the investigative phase of criminal cases, generally conducted in private and without the participation of the person under investigation.
In future House Judiciary Committee hearings that presumably would result in the drafting of impeachment articles, Trump would be invited to attend and his lawyers could question witnesses and object to testimony and evidence, similar to the process in the impeachment proceedings against Presidents Richard Nixon and Bill Clinton.
If there is a Senate trial, Trump's legal team would defend the him against impeachment articles approved by the House in an environment that would look like a typical trial in some respects.
WHERE'S THE CRIME?
The hearings may feature debate over what constitutes a crime for purposes of impeachment. If so, that may be beside the point.
Under the Constitution, impeachment involves a political judgment about whether public officials have abused their office to the detriment of the country and therefore should be removed from that office.
A crime may establish that condition. But a president could still be subject to impeachment even if the conduct is not a crime.
Soliciting or accepting election help from a foreign entity is illegal. But it's not clear that the overseas investigation sought by Trump qualifies as an illegal campaign benefit. It does not need to qualify as one if Congress renders the judgment that it's an abuse of office.
Expect Rep. Adam Schiff, the public face of Democrats' impeachment inquiry who will open the hearings, to be a frequent target of Trump and Republican lawmakers. Trump has even called on the intelligence committee chairman to be made to testify as a witness subject to cross-examination.
In Trump's eyes, "Shifty Schiff" is guilty of almost everything: fabricating Trump's conversation with Ukraine's president, writing the whistleblower's complaint himself, treason. None of that is true.
"Didn't he pick the Whistleblower?" Trump tweeted Nov. 2.
"It's a scandal he knew before. I go a step further. I think he probably helped write it," Trump told reporters Oct. 2.
The whistleblower did speak to staffers on the House Intelligence Committee on procedural issues before filing the formal complaint that would trigger the impeachment inquiry. But Trump and his GOP allies are taking a big leap in asserting that Schiff schemed with the whistleblower to lodge the complaint.
Patrick Boland, a spokesman for Schiff, said that committee staff advised the person to contact an inspector general and to seek counsel, but that the committee did not get an early look at the complaint.
The whistleblower's lawyer, Mark Zaid, said the person had never met or spoken with Schiff about the matter.
Trump also has repeatedly claimed that Schiff "illegally made up a FAKE & terrible statement" about his Ukraine phone call, sometimes asserting that the California Democrat was then caught in "a total lie" after Trump released a rough transcript of the call. Trump has branded Schiff's acts treason.
Trump is exaggerating the episode and botching the timeline.
Schiff delivered what he called a parody of Trump's remarks on the July 25 phone call with Ukraine's leader.
Schiff did so after the White House released a rough transcript of the call, not before. So people who read the official account knew Schiff was riffing from it, not quoting from it.
Trump loosely throws around accusations of treason, extending it, for example, to Democratic immigration policy and negative newspaper coverage.
Under the Constitution, treason occurs when a U.S. citizen, or a noncitizen on U.S. territory, wages war against the country or provides material support to a declared enemy of the United States. It is defined narrowly as part of an effort by the framers to prevent the government from using it as a reason to suppress political speech. No one has been convicted of treason since the aftermath of World War II.
THE 'NEVER TRUMPERS'
Trump says the arguments against him are "made up garbage by Shifty Schiff and the Never Trumpers!"
His point misrepresents the breadth of the testimony heard in the closed-door hearings. The witnesses are not all hostile to Trump or part of a cabal against him.
Problematic testimony has come from people who worked assiduously to get Ukraine to do what Trump wanted. Among them: Gordon Sondland, a wealthy donor to Trump's 2016 campaign whose loyalty was rewarded with his appointment as U.S. envoy to the European Union.
Reversing a key point of his testimony, Sondland said he had conveyed to a Ukrainian official that the country's leadership would need to announce an investigation of the Bidens and Democrats as a condition of getting the military aid that Trump had frozen.