Washington (CNN) The imminent final act of America's impeachment ordeal will be played for far higher political stakes than might be expected given the all-but-guaranteed acquittal of President Donald Trump in his trial in the Republican-led Senate .

The long wait for the trial to begin -- nearly four weeks pulsating with political gamesmanship after the House voted to consign Trump to historic ignominy -- finally looks to be over.

House Speaker Nancy Pelosi, a California Democrat, will meet her troops on Tuesday and is expected to finally relent in her refusal to send the articles of impeachment to the other chamber -- a delay triggered by a bid to dictate the terms of the trial.

Finally, the Senate will get the chance to assess whether Trump, the third president ever impeached by the House, is guilty of the standard of "high crimes and misdemeanors" for trying to coerce Ukraine to dig up dirt on his possible 2020 election foe Joe Biden.

The way that the public comes to view the climax of the scandal will shape the rest of the President's term, his hopes for a second one and the destiny of the Senate come November's elections.

Democrats hope to brand Republicans as shielding a historically corrupt President and to create a powerful line of argument for their eventual 2020 nominee, who will argue the episode shows Trump is unfit to stay in the White House.

But Trump is certain to view his escape as vindication of an impulsive and unchained leadership style -- while Republicans compete to show fealty to a President who dominates his party like few of his predecessors.

The speaker is using every last drop of her power to keep Washington on tenterhooks. Asked by CNN on Monday whether she had chosen impeachment managers to make the case in the Senate that Trump abused his power in Ukraine, then covered it up, she replied: "When I do, I'll let you know."

House Democrats are expected to vote as early as Wednesday to appoint the mangers, a step that will grind constitutional gears across the Capitol, where senators will be sworn in and the dramatic trial steered by Supreme Court Chief Justice John Roberts will begin within days.

The multiple political games inside the impeachment puzzle

Nothing will change the fact that Trump is in the most dubious club in presidential politics in perpetuity. Only Andrew Johnson and Bill Clinton share that legacy-defining fate. But the battle now is over more immediate politics. That's why the feud between Republicans and Democrats over witnesses is so important.

Democrats believe that the witnesses they already called in the House investigation and hope to hear from in the Senate paint a picture of an unaccountable and corrupt presidency that could scare uncommitted voters.

By highlighting the resistance of Republicans like Senate Majority Leader Mitch McConnell of Kentucky to hearing such testimony, they can accuse the GOP of covering up for a malfeasant President.

"Most Americans know President Trump ... seems to be afraid of the truth," Senate Minority Leader Chuck Schumer, D-New York, warned Monday. "A trial without all the facts is a farce. The verdicts of a kangaroo court are empty."

Republicans have little interest in unearthing new and questionable conduct by the President or in shining a light on damning testimony from foreign-policy officials about Trump's conduct heard in the House.

The GOP leadership is under pressure both to orchestrate Trump's swift acquittal to please base voters and to shield vulnerable incumbents as they battle to keep control of the Senate.

Recent polling shows that both sides have an interest in playing to their most committed supporters -- whatever the Constitution envisions about the chamber acting as a nonpartisan arbiter of presidential behavior.

In a new Quinnipiac University survey, 51% of voters approve of the House vote to impeach Trump, but a slightly smaller sample -- 46% -- think the Senate should vote to remove him from office.

The GOP argues that it is not the Senate's job to continue investigating, especially after House Democrats opted not to take legal action to compel witnesses like former national security adviser John Bolton to testify.

What did Pelosi gain?

Pelosi, who says her delaying tactics allowed more time for critical evidence to emerge, is urging McConnell to call for new documents and witnesses that the White House has so far refused to provide.

"Now the ball is in their court to either do that or pay a price," the speaker said on ABC News' "This Week."

But Pelosi failed to force McConnell to agree to a plan to hear from a slate of witnesses before the trial begins.

"In terms of influencing Senate proceedings, this strange gambit has achieved absolutely nothing," the majority leader said on Monday.

Still, McConnell is not in complete control. He cannot afford to lose more than three senators on his own side in procedural votes. And several GOP senators have expressed disquiet about the way in which he has coordinated Trump's defense with the White House.

Sen. Mitt Romney of Utah said Monday, for instance, that he would "like to hear" from Bolton -- but stopped short of calling for him to be subpoenaed.

Sen. Lisa Murkowski of Alaska told reporters she's working on a process to hold votes on witnesses and possible information if necessary.

According to sworn testimony in the House investigation, Bolton viewed Trump's Ukraine fixer and personal attorney Rudy Giuliani as a "hand grenade." The former national security adviser now says he'd be willing to appear at the Senate trial if subpoenaed, though the White House is likely to seek to limit his testimony with assertions of executive privilege.

At one point, the President was itching for a show trial, along with witnesses that could tar Biden over claims that he and his son Hunter were guilty of corruption in Ukraine. There is no evidence to substantiate such charges.

Then the President seemed to be pulling for a quick acquittal that he could use on the campaign trail. Now he's calling on Republican senators to crush the charges as soon as they arrive.

"Many believe that by the Senate giving credence to a trial based on the no evidence, no crime, read the transcripts, 'no pressure' Impeachment Hoax, rather than an outright dismissal, it gives the partisan Democrat Witch Hunt credibility that it otherwise does not have. I agree!" Trump tweeted Sunday.

But such a strategy would be almost certain to backfire.

"I think I am safe in saying there is almost no interest in a motion to dismiss," Sen. Roy Blunt of Missouri, a member of the Senate leadership team, told reporters on Monday.

"Certainly, there are not 51 votes for a motion to dismiss," he said.

Despite the President's preferences, the White House has been preparing hard for the trial. White House counsel Pat Cipollone has been working on Trump's defense for weeks. He's expected to work in harness with the President's outside attorney Jay Sekulow -- a smooth television performer.

CNN confirmed on Monday that Giuliani has lobbied Trump for a place on the Senate floor. But the President's attorney has become known for inflammatory television appearances that leave more questions than answers about his client's behavior.

And Giuliani is a witness to much of Trump's off-the-books diplomatic scheme in Ukraine and might become a gift for Senate Democrats.