At some point in the next few months, maybe even the next few weeks, Donald Trump will almost certainly become the third president to be impeached by the House of Representatives. After Tuesday’s explosive testimony by William Taylor, the senior American diplomat in Ukraine, there is no plausible way that outcome can be avoided.

Taylor laid out for House investigators how Trump blocked military aid to Ukraine — aid duly appropriated by Congress — in order to force the country’s new president to publicly announce that he would launch investigations into former vice president Joe Biden and alleged Ukrainian interference in the 2016 election. According to Taylor, a West Point graduate and former Army officer who has held positions in every presidential administration since Ronald Reagan’s, he was told bluntly that “everything” the Ukrainian leader wanted from the White House “was dependent on such an announcement.” Unless Taylor’s evidence is refuted — so far it seems rock-solid — Congress now has contemporaneous confirmation that Trump engineered the shakedown of a foreign government to inflict political damage on a domestic opponent, in the process undermining strategic US interests in Europe.

So Trump will be impeached by the Democratic-controlled House. Will he be convicted by the Republican-controlled Senate? As things stand now, no — but who knows what else the impeachment inquiry will reveal? Among Republican voters, Trump continues to enjoy overwhelming popularity. So did Richard Nixon well into the Watergate scandal. But when the collapse came, it was swift. For years, Nixon had relied on support from a “silent majority” of voters, who stood with him despite the contempt in which he was held by elite liberals. That support evaporated, however, once it became clear that Nixon had indeed obstructed justice and abused his powers.

To remove Trump in an impeachment trial would require at least 20 Republican senators to vote for conviction. Unless the president’s 90 percent approval rating among the GOP rank-and-file begins to shrivel, that won’t happen. But sky-high poll numbers have a way of falling to earth. At the moment, Republican senators may be wary of opposing a president so strongly backed by the voters they depend on to ward off primary challengers. Let doubts appear among the party faithful, though, and all bets are off.

Those doubts are overdue. Trumpism has been terrible for Republicanism. It certainly hasn’t delivered electoral success. Trump famously predicted that if he became president, Republicans would “win so much” that they would grow “sick and tired of winning.” Yet the Trump era has been one of sustained Republican losses.

Last November, Democrats not only recaptured a majority in the US House, they also flipped more than 300 state legislative seats and picked up seven governorships. They now control a majority of state attorneys general offices. Under Trump, GOP prospects have grown so bleak, and the party’s image so tarnished, that dozens of Republicans in Congress have opted not to seek reelection. Young people are fleeing in droves. The “Never Trump” Republicans — or “human scum,” as the president charmingly describes them — are gone too. As of last summer, registered Democrats outnumbered registered Republicans by 12 million.

Trump’s 2016 takeover of the Republican Party was a political earthquake, powerful and unexpected. Like most earthquakes, it has left terrible devastation in its wake, including to the GOP itself. Rebuilding the party and salvaging its reputation won’t be easy — not with impeachment virtually a foregone conclusion. But even if Trump, like Andrew Johnson and Bill Clinton, survives his Senate trial, do Republicans really want to be saddled with him for another term?

For principled conservatives and loyal Republicans, the Trump presidency has delivered some undeniable benefits: two Supreme Court justices and multiple appellate judges, a significant tax cut, the repeal of the Obamacare mandate, abrogation of the Iran nuclear deal, and meaningful regulatory relief, all accompanied by impressive economic growth and record-high employment. But those gains have come at a terrible price: three years of immigrant bashing and chaotic trade wars, of ugly fights with foreign allies and sucking up to hostile dictatorships, of nonstop Twitter insults and falsehoods large and small, of unprecedented turmoil within the White House and unhinged encounters with the press.

The Trump years have turned American politics into a screaming freak show. They have tarnished our standing around the world and embittered our civic discourse at home. The original Republican president, Abraham Lincoln, implored his countrymen to heed “the better angels of our nature.” Ronald Reagan, the 20th century’s greatest Republican president, told Americans he “appealed to your best hopes, not your worst fears; to your confidence rather than your doubts.” Trump does the opposite.

The Republican Party desperately needs a new standard-bearer. In 2016, the GOP allowed itself to be taken over by an unworthy and indecent scoundrel. Now, following an endless train of scandals and abuses, that scoundrel is about to be impeached. This would be a good time for his party to jettison him, as Republicans jettisoned Nixon. America is blessed with many honest, admirable, competent conservatives. The Republican Party ought to nominate one of them for president in 2020. One term of this exhausting, disordered, toxic administration is enough. What is needed now is a candidate who can make America normal again.

(Jeff Jacoby is a columnist for The Boston Globe).