(CNN) America's latest "national nightmare" will not end when Republicans vote to acquit President Donald Trump of high crimes and misdemeanors, possibly as early as Friday.

A mere four months after House Speaker Nancy Pelosi ordered an impeachment inquiry and six after Trump's now notorious "do us a favor" call with Ukraine's President, Trump will get on with his term as the third US President to be impeached by the House of Representatives and not removed by the Senate.

Given Trump's political temperament, and the impending battle between the parties for control of the White House, it seems unlikely there will be a healing voice to help reconcile a divided country -- such as President Gerald Ford's, when he declared that "our long national nightmare is over" in the wake of Watergate.

The President will skip free despite strong evidence to suggest that he abused a public trust by trying to coerce a foreign power -- with millions of dollars in taxpayer cash -- to play a role in a US presidential election. The many unresolved storylines and loose ends of this divisive episode will ensure that the political significance of his off-the-books diplomatic scheme in Kiev may only become more corrosive with time.

Thanks to the estranged political realities of the age, Trump is likely to interpret his latest escape, in a business and political career that has often flirted with disaster, as an inducement to broaden his crusade to expand his personal power and shake off remaining constitutional guard rails.

Still, the side effects of the showdown will reverberate for years and subsequent political eras. It will claim short-term victims — maybe even including the President or those who pursued him with elections only nine months away. But the dramatic events at the turn of 2019 and 2020 could also change how future generations understand presidential power and the process of purging its abuse by the use of impeachment itself.

Unknown consequences for November

Most immediately, the unsuccessful effort to oust Trump will help shape November's election that may partially be framed around whether Republicans pay a price for saving him or Democrats get a backlash for impeaching him.

Democrats hope that months focusing on apparent abuses of power by Trump will have soured crucial swing-state suburban voters irrevocably against him. But they'll worry they electrified Trump's base.

Republicans may prevent further damage to the President by preventing the calling of witnesses with potentially incriminating evidence such as former national security adviser John Bolton in a closely watched vote Friday. Some GOP members have told their leaders that they just want to get the trial over with -- since even its two weeks on the Senate floor have damaged their reelection prospects, CNN reported.

Sen. Lamar Alexander, a retiring Tennessee Republican, all but assured no witnesses would be called during the trial when he announced late Thursday night that he would vote against a motion to call them. Alexander was seen as the most likely potential fourth Republican to vote in favor of hearing witnesses. His decision appears to end Democratic hopes of hearing from Bolton under oath despite a willingness from GOP Sens. Susan Collins and Mitt Romney to hear from witnesses.

With this in mind, it's possible Democrats benefit politically from the chance to lambast what happened in the Senate over the last two weeks as a mockery of a fair trial. Still, they would have loved to have had Bolton on the record to further color a dark picture of Trump's behavior.

Republicans will take a risk by blocking witnesses. They elected to perpetrate what Democrats will find easy to portray as a cover up by suppressing a chance to hear Bolton — a witness with information about the core accusation in the impeachment case — from telling his story.

"You cannot be acquitted if you don't have a trial, and you don't have a trial if you don't have witnesses and documentation," Pelosi said on Thursday, already excavating a seam of post-impeachment politics.

When the former national security adviser's information -- contained in the manuscript of a book first reported by the New York Times -- eventually comes out, GOP lawmakers must hope that it does not leave them badly exposed. As it is, history may remember the 2020 GOP as making a choice between power and political short-termism and shielding the Constitution and accepted codes of presidential behavior.

But in the absence of large numbers of GOP senators willing to fall on their swords in an altruistic rebuke of Trump's behavior, the dynamics of their party in the Trump era left them little choice.

The experience of impeachment will certainly tighten the bond between Trump and supporters who have just watched their champion once again defy the efforts of a Washington establishment to rein him in.

Trump's capacity to browbeat GOP senators into supporting him, even if some harbor doubts about his behavior reflects his greatest political success — the transformation of the Republican Party in his own fact-denying image.

Impeachment saga exposes national divide

The trial is a reminder of the gaping political disconnect down the middle of the nation. While Democrats and members of the Washington media and political establishments express horror at this presidency's slash and burn approach to the Constitution, many Trump supporters don't care.

Only 8% percent of Republican respondents believed Trump should be removed from office in a CNN poll conducted earlier this month, compared to 89% of Democrats.

Such figures are the payoff for Trump's relentless effort to reward his political base on issues like immigration, foreign policy and conservative judges, his clever use of cultural issues like gun control and abortion and his refusal to moderate the outsider, outlandish behavior that got him elected.

It is to those committed Trump voters to whom Republican senators must return every weekend. This is one reason why a senator like Cory Gardner from Colorado — endangered in a state trending away from Trump -- still cannot extricate himself from the President and his fervent base voters sufficiently to vote to hear new witnesses like Bolton.

In this context comments by Republicans that seem to jar with the facts and the weight of evidence in the trial can actually be explained.

"I think for most Americans they want us to move on to something that actually matters for them," one of Trump's top allies in the House, Republican Rep. Mark Meadows of North Carolina, said on Thursday for example, perhaps thinking of the large majority of conservatives in his district.

The hyper-political nature of the aftermath of the impeachment fight shone through the Senate trial on Thursday when one of the President's attorneys took time out to praise the President's three years in office -- seemingly that his approval rating justified any extremes of behavior.

"We, the American people, are happier," said Eric Herschmann -- trying to put some flesh on the bones of a controversial case laid out by his colleague Alan Dershowitz that a President acting in the belief that his reelection in the nation's interest could not by definition carry out an impeachable act.

"And yet the House managers tell you that the President needs to be removed because he's an immediate threat to our country," Herschmann said.

Adopting Trump's campaign trail mantra, Herschmann touted a strong economy, the killing of terrorists and slowed border crossings.

"If all that is solely — solely, in their words — for his personal and political gain and not in the best interests of the American people, then I say, God bless him. Keep doing it," Herschmann said.

Constitutional shockwaves

Longer term, the end of Trump's trial will mark a profound political moment.

The President's defense team — beset by inconvenient facts about Trump's pressure on Ukraine for dirt on Joe Biden and other Democrats — resorted to a staggeringly broad concept of presidential power for his actions.

That gave Republican senators a hook to argue that what Democrats charged as abuse of power and obstruction of Congress was in fact perfectly permissible behavior. But it lays down a blueprint for vastly enhanced inferred powers of the presidency for Trump and his successors.

It doesn't follow that all presidents will now seek to force vulnerable overseas powers to come up with political payoffs. But it could convince unscrupulous future occupants of the Oval Office to reason they might get away with it. Foreign adversaries keen to discredit US democracy could have a field day.

The implied expansion of presidential power that will be left in this impeachment saga's wake seems to be turning back the clock to before the time of Richard Nixon's ouster in the Watergate scandal. After that original "long, national nightmare" Congress sought to recover powers from White House that had been abused by the 37th President. But gradually, the presidency has adopted a more imperial mode starting with the Reagan administration through George W. Bush and Barack Obama. But none of those presidents -- who were sometimes criticized for overreaching executive authority on issues like union policy, anti-terrorism measures and immigration -- made the kind of audacious power grabs that have characterized Trump's administration and for which he has now been absolved.

Lead House impeachment manager Adam Schiff warned on Thursday that the constraining of the presidency in the years after Watergate had now been reversed -- to dangerous effect.

"We are right back to where we were a half century ago," Schiff said. "And I would argue we may be in a worse place."

"That argument, if the President says that it can't be illegal, failed," he continued. "And Richard Nixon was forced to resign. But that argument may succeed here now. That means we're not back to where we are, we are worse off than where we are. That is the normalization of lawlessness."