Trump's removal from office is far from certain but neither is his acquittal

Mr Trump has asked the Senate to quickly dismiss charges

(FILES) In this file photo taken on January 9, 2020 US President Donald Trump speaks during a "Keep America Great" campaign rally at Huntington Center in Toledo, Ohio. The head of a Canadian food giant appeared to blame US President Donald Trump for the deaths of Canadians, including an employee's wife and child, in the downing of a jetliner in Iran. The Ukraine International Airlines Boeing 737 was shot down by a missile shortly after taking off from Tehran before dawn last January 8, 2020, killing all 176 passengers and crew on board. Fifty-seven of the victims were Canadian. Maple Leaf Foods chief executive Michael McCain said late January 12, 2020 in a Twitter message that a colleague lost his wife and child to a "needless, irresponsible series of events in Iran."

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On the eve of his impeachment trial which will begin in the Senate next week, time is clearly not on the president's side, even if the rushed schedule, which suits both Republicans and Democrats, might be.

US President Donald Trump finally secured a Ukrainian criminal investigation announcement, although certainly not the one he was hoping for. He wanted Ukraine to investigate his rivals, but the Kiev government has announced a criminal probe into his allies instead.

Unsettling information continues to accumulate about the activities of the president’s close associates, particularly Mr Trump’s private attorney Rudy Giuliani and the latter’s operatives. Leaked text messages recently revealed, for instance, that this gang may have had the movements of former US ambassador to Ukraine, Marie Yovanovitch, under surveillance during 2019.

Democrats are insisting that there is no such thing as a trial that does not involve testimony by witnesses and the subpoenaing of relevant documents

The people involved claim to have been joking, under the influence of alcohol, or "playing." But these and other astonishing revelations leave little doubt that there is much more about the Ukraine scandal that remains to be discovered.

The obvious need for additional information, and the well-known sources from which it could be obtained, will be at the heart of what is only the third presidential impeachment trial in US history.

Democrats are insisting that there is no such thing as a trial that does not involve testimony by witnesses and the subpoenaing of relevant documents. The impeachment inquiry in the House of Representatives was akin to a grand jury investigation or the preparation for an indictment, which the House adopted in the two articles of impeachment adopted on December 18.

Indeed, there has never been an American impeachment trial without witness testimony or new documents, including both previous presidential impeachments. Yet such an unprecedented scenario is exactly what Senate Majority Leader Mitch McConnell and his Republican colleagues are hoping to engineer.

Mr McConnell and most of his GOP colleagues have made it clear that they intend to acquit Mr Trump no matter what, and that they are not interested in any evidence whatsoever. Indeed, he derisively says that House Democrats did a "rushed and incomplete job" and are asking the Senate to "do their homework for them."

This elides the obvious point that the House’s motivation for handing the Senate a remarkably incomplete file to support the “high crimes and misdemeanours” (for which presidents may be impeached) is that the White House has flatly refused to share any documents with the impeachment inquiry. Furthermore, it has attempted to block all executive-branch officials from testifying. Some relatively junior or former officials testified anyway, but all the key witnesses who dealt directly with Mr Trump have not been heard from, and a raft of crucial documents remains unexamined.

Mr Trump has asked the Senate to quickly dismiss these charges, and while Mr. McConnell doesn't appear ready to do that, he is clearly determined to prevent any more information coming to light. Given the revelations in the past few weeks, and the obvious fact that Republican senators have no idea what else may be discovered, their anxiety is understandable.

During the House hearings, a parade of witnesses managed to paint a remarkably intricate picture of a president determined to hijack US military aid to Ukraine to secure the announcement of a baseless criminal investigation into the son of his political rival, Joe Biden. But because the White House successfully blocked all the senior-most potential witnesses, the president's own role was not described in great and direct detail.

Obviously, if Mr Trump and Mr McConnell were confident he had done nothing wrong, they would welcome a closer examination of the facts.

The problem is particularly acute for Mr McConnell. As damning recent revelations demonstrate, additional facts are liable to put him in an impossible situation, given that he simply does not care what the president may have done and is determined to acquit him no matter what.

Worse, Mr Trump knows exactly what he did and didn't do, but Senate Republicans don't. They really have no idea what remains to be discovered and what is already on the record is bad enough to place them in an awkward position. Despite their best efforts, this problem is only likely to get worse.

Like war, a trial is among those social processes in which the outcome and, in retrospect, the underlying realities appear very different at the end of the process than they did at the beginning. Mr McConnell knows this, and that explains his insistence on a short and essentially meaningless "trial."

Even though he commands a Republican majority in the Senate, he may not get his way, at least not entirely.

Mr Trump's Senate trial will hinge upon the procedural rulings of a Senate majority, with Chief Justice John Roberts serving as a tiebreaker when necessary. In practice, this means that only three or four Republicans need, at any stage, to side with Democrats on a motion to hear certain witnesses – one example being former national security advisor John Bolton, who has said he would testify and that he has significant new information.

As things stand, few if any Senate Republicans appear willing to convict Mr. Trump and remove him from office. However, a small group might be amenable to siding with Democrats, and possibly the Chief Justice, in insisting on additional testimony and documents. Once that process is unleashed, there is no telling where it might lead.

Under the current circumstances, it's very hard to imagine the Senate voting to convict and remove Mr Trump from office, despite an already strong case that he did, indeed, abuse the powers of his office for personal political gain and, as his defiant attitude suggests, would likely do so again.

But one thing is certain on the eve of this momentous Senate trial: anyone who has complete confidence in its outcome and impact is living in a fool's paradise.

What we are about to witness is a process that isn't wholly predictable or under anyone's firm control.

Hussein Ibish is a senior resident scholar at the Arab Gulf States ­Institute in Washington