House Democrats crossed the Rubicon this week and committed, for the record, to their impeachment inquiry. Although they said impeachment isn't a foregone conclusion, they tried to underscore again that this is serious.

Meanwhile, more confirmations of the facts of the Ukraine affair meant the end of the investigation process may now be in view — and public hearings could be coming next.

Here's what you need to know about the events of a historic week in Washington and what may be around the corner.

Lt. Col. Vindman and Mr. Morrison

House investigators heard from two more witnesses who confirmed the underlying facts of the Ukraine story: President Trump sought to pressure the Ukrainian government to launch investigations that he believed would help him in the 2020 election.

Lt. Col. Alexander Vindman and, later, Timothy Morrison — two top White House policy officials — are believed to have told investigators about the parallel foreign policy being run by Rudy Giuliani; the use of hand-picked diplomats, including the U.S. ambassador to the European Union, Gordon Sondland; and the discomfiture of career professionals about what was taking place.

Both men listened to Trump's now-famous July 25 phone call with Ukraine's President Volodymyr Zelenskiy. Their subjective impressions about what they observed, however, were different.

Vindman said he thought almost immediately that what he had heard was problematic.

He pushed for Trump to reinstate the military assistance to Ukraine during the time it was frozen and also for the White House to restore terms that Vindman remembered Trump using, including references to the investigation that Trump wanted into the family of former Vice President Joe Biden.

Morrison told House investigators he didn't think Trump had done anything illegal, but he opposed the Ukraine pressure strategy on its merits because it helped Russia — and he also realized that there would be political blowback both in Kyiv and Washington if details of the call were revealed.

The vote

Meanwhile, the House voted on Thursday to make its impeachment inquiry formal.

The measure passed 232 to 196 with no Republican support. Two Democrats joined Republicans in opposing the impeachment inquiry.

Trump and Republicans had complained that House Speaker Nancy Pelosi's announcement about an inquiry didn't carry the same legal weight as an actual vote and, accordingly, it was illegitimate.

That was one reason why White House counsel Pat Cipollone vowed that the administration would not cooperate with witnesses or evidence.

But that firewall hasn't stopped several current administration witnesses. The House vote also didn't change the minds of Republicans either. They rejected the framework set out in the legislation as still too unfair to them and the due process they say they and Trump are owed.

'Legitimate actions'

House Minority Leader Kevin McCarthy, R-Calif., also offered a substantive defense of Trump.

In a floor speech opposing the impeachment inquiry, McCarthy said that Democrats were abusing "secret process and selective leaks to portray the president's legitimate actions as an impeachable offense."

Translation: Trump had the power and was within his rights to expect concessions from Ukraine in the way he did and should not be impeached, for McCarthy.

Other supporters, including Sen. Rob Portman, R-Ohio, have reached that conclusion by traveling a different route, arguing that although they believe Trump's actions weren't appropriate, the president shouldn't be impeached.

Pelosi, who arrived late to Democrats' impeachment bandwagon, was unfazed.

"This is a solemn occasion," she said. "The times have found every one of us in this room."

Trump, in her telling, has abused his powers so badly and rejected Congress so flagrantly that, for Pelosi, the House has no alternative but to consider impeachment.

Then she said something important: "That decision has not been made ... that is what this inquiry will determine."

Collision course

Members of Congress in both the House and the Senate appear to expect an old-fashioned impeachment; Senate Majority Leader Mitch McConnell, R-Ky., has circulated plans for how an eventual trial might run later this year, as NPR's Susan Davis and Claudia Grisales reported.

The concession by Pelosi this week, however, holds open the possibility that she and Democrats might wave off before they got there. Impeachment is an indictment by the House that would spark a trial in the Senate.

The upper chamber is controlled by McConnell and the president's allies, and unless there's a major change in the political atmosphere, Trump seems likely to be acquitted and keep his office.

That's why Trump and supporters have long calculated that impeachment might wind up being a political asset for them. The Trump campaign says impeachment is already helping its fundraising.

Democrats can see this situation as clearly as anyone else. That's why it was telling that Pelosi said Thursday that impeachment isn't necessarily automatic. All she has done is commit the chamber to an inquiry. If the political headwinds pick up, it raises the possibility that Democrats might try to find some other outcome besides a Senate trial in which Trump prevails.

Going active

If Pelosi and her lieutenants have been encouraged by public polls that suggest support from many Americans — albeit almost no Republicans — the final test may come after the next phase in the inquiry.

Democrats have invited another slate of White House witnesses for closed-door depositions next week, including former national security adviser John Bolton. They may not appear, citing Cipollone's instructions not to cooperate. Energy Secretary Rick Perry has also been invited, but his department says he will not participate.

There may not be many more closed-door sessions, and instead, Democrats may prepare to shift from the inside game to the outside game.

For one thing, investigators are expected to release hundreds of pages worth of depositions, like those from Vindman, Morrison and many others.

Democrats also are expected to convene open hearings in which some witnesses who've already testified, including, potentially, Ambassador William Taylor, could tell their stories in the open.

Republicans would have some privileges in these proceedings, including the ability to call witnesses of their own with the assent of the committee chairman.

The impeachment inquiry resolution also directs the publication of a final report about the committees' findings, which likely would form the basis for any eventual articles of impeachment.

The House Judiciary Committee has jurisdiction over that legislation and that process, as NPR's Deirdre Walsh wrote, and it would be under the aegis of its chairman, Jerry Nadler of New York, that impeachment could move to the House floor and a final vote.

McConnell has said that if he receives impeachment articles from the House, the Senate will convene a trial as designated under the Constitution.

The trial

The 100 members of the Senate would be the jury; they would be expected to sit in their seats without speaking — a spectacle rarely glimpsed — while impeachment managers from the House made the case for and against removing Trump.

John Roberts, the chief justice of the United States, would preside and manage the byplay on the Senate floor as his predecessor, William Rehnquist, did when President Bill Clinton was impeached in 1998.

So far, so familiar. And if present dynamics hold, Trump, like Clinton, would be acquitted and preserve his office.

If the Senate were to vote to remove Trump, however, Washington would go from an already seldom-seen practice in impeachment and truly sail off the map completely.

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