Two weeks ago, I wrote of the unusually important parallel campaigns, for the presidential nominations in the United States and over whether the United Kingdom would continue within an “ever closer” European Union. I was in Britain last week, and have an update on both contests — which are now slightly intertwined, because of President Obama’s wildly egotistical effort, on invitation from the beleaguered British prime minister, to be a deus ex machina for the forces of “Remain” in the U.K.

The great schism yawns ever more cavernously between a severely politically disappointed American public and the official and press personalities whose antics disappoint them. Even at this late date, even the most knowledgeable are inexplicably reticent to recognize how profoundly the antics of the political class of the last 20 years have alienated an immense bloc of the electorate.

Donald Trump’s sweep of five states on Tuesday, bagging enough delegates to get him to around 975 of the 1,237 needed to nominate, and nearly 400 ahead of Senator Cruz, probably does not much reflect public reaction to the shabby effort of Messrs. Cruz and Kasich to pool their votes according to which is stronger in the remaining individual primaries. But it does show that Donald Trump has graduated from a protest candidate to a favored front-runner in states that are generally rather liberal, even among Republicans, and would have been thought inaccessible to a flamboyant billionaire who has never before sought public office.

Mr. Trump’s speech on foreign policy to the National Press Club on Wednesday discloses a sensible conception of America’s national-security interest, and the candidate’s determination, if elected, to demarcate a sustainable definition of that interest, with suitable consultation with proven allies, especially the other English-speaking powers (Great Britain, Canada, Australia, and New Zealand). He clearly lays out a middle course in which the United States will negotiate any disagreements with China and Russia from a position of military and diplomatic strength, and will revitalize the Western Alliance by abandoning the Obama administration’s perverse effort to make allies out of enemies. He has also pledged not to revert to George W. Bush’s reckless war-making and imposition of democracy on non-democratic allies, which has promoted Hamas, Hezbollah, and the Muslim Brotherhood. It is a cogent and persuasive address that should end the campaign to portray Mr. Trump as a blundering warmonger.

The anti-Trump forces, which began by disparaging his candidacy as a beau geste brand-building exercise, capped at 20 percent in the opening primaries and petering out thereafter, and have seen his support rise to almost 50% of Republicans, have now, in a final act of desperation, attempted a fusion of candidacies without a withdrawal: Cruz and Kasich are to stand back and support each other in the races where one is clearly ahead of the other. I wrote here more than a month ago that the efforts of the traditional Bush Republicans to ostracize Mr. Trump would elicit Lyndon Johnson’s famous “frontlash,” in which those who objected to such cynicism would exceed the numbers of those who fell in with it.

Neither candidate has withdrawn, even from any of the remaining primaries; it is an uneasy half-reach between candidates who bracket Mr. Trump in policy terms and are too appalled at each other to make a formal alliance. They are like two young teenagers playing “I’ll show you mine if you show me yours.” Most of the followers of both would probably rather have Mr. Trump than the other.

It is anachronistic for Jeb Bush to endorse Mr. Cruz, the candidate of government shutdown. Once again, the forces of Republican continuity have failed to grasp that most Republicans and most Americans want to defenestrate into the oblivion of fading memory all those even remotely responsible for the unspeakable sequence of blunders of the last 20 years.

Governor Kasich, running as Mr. Rogers, advising us to “hug a stranger in the mall” and “invite a widow to dinner,” has thrown in with the most reactionary claimant of a serious presidential nomination since James Gillespie Blaine in 1884. Mr. Cruz is a pure conservative, pitching irreconcilable capitalism, and the steamrollering of any twinge of compromise in the capital. And Mr. Kasich, an almost submerged representative of the old Republican center, has been persuaded to assist in trying to salvage Indiana for Mr. Cruz, which is all that will revive a hope of a second ballot at the Cleveland convention in July. It will fail, and these two candidates throwing each other waterlogged life preservers will sink like Senator McConnell’s “hot rock.”

Even the splendid and redoubtable Peggy Noonan wrote, in the Wall Street Journal on Saturday, that she had had her “campaign moment” when the abrasive and sometimes repulsive coarseness of this campaign convinced her that we were not going to hear candidates of the personal suavity, and eloquence, of Franklin D. Roosevelt, John F. Kennedy, Martin Luther King, and Ronald Reagan. The new Donald Trump will be less troubling than he has been in this respect, but the real reason for such a “campaign moment” is that the people who are the surging crowds in this campaign are too angry for that.

FDR was addressing extreme national concern, first over the Great Depression and then over the Nazi and Japanese-imperialist threat to democratic civilization. JFK was trying to sell youth, religious tolerance, and a fresh intellect to a nation that had had seven terms of very capable leadership from presidents the age of or a little older than JFK’s father. Martin Luther King had every right to be a good deal more crudely angry than anyone prominent in this election (and probably was in private), but not if, as was his inspired tactic, he was going to mobilize the majority of white America to the black cause.

And Ronald Reagan was moving the whole field, and not just one set of goal posts, to the right, and had to reassure, with the infallible benignity of his sometimes almost hypnotic oratorical skills, those whom his opponents attempted to frighten. In this election, Donald Trump has tapped into the anger, frustration, and fear of the scores of millions of voters who feel no one cares about them while the flabby, complacent ranks of the phony Bush-Clinton joint dynasty shift between comfortable deck chairs on what will become the great American Titanic unless there is a course change.

Mr. Trump has won the attention of those voters and has now shifted his sights upwards to the rich Republican stomping grounds of the boardrooms and country clubs, as well as the sober middle class. He is the moderate in this race, close to Mr. Kasich in policy, well to the center of Senators Cruz and Sanders (approaching from opposite extremes), and the natural claimant on much more of the center than Hillary Clinton. He has corralled the angry and financially stretched working class and can now assuage the concerns of traditional prosperous Republicans who have been spooked by the noisy billingsgate of the early campaign.

It is time to retake the center, which Mr. Trump has the policies to do. Reagan did it with sonorous eloquence, Nixon with tactical skill, and Mr. Trump can do it by his unexceptionable moderation in all areas except rhetorical treatment of Mexican immigration and misconceived trade pacts. He is no Reagan, nor even Nixon, as a public tribune, but he is not complicit in the misgovernment of the last 20 years, he is a proven manager and deal-maker, and he isn’t his opponents.

I have written here several times that Mr. Trump was not necessarily my preferred candidate, but this latest skullduggery, by which Mr. Cruz robbed Mr. Kasich of his ethical virginity by ceding to him two states of no current importance, makes Donald Trump the only respectable candidate. Mr. Sanders is a nightmare; Mrs. Clinton is a hackneyed, tainted, spavined wheel-horse. Mr. Cruz is unfit for the office he seeks: His intelligence and most of his policy opinions are not in dispute, but he is too tactically villainous for the headship of the American people, at least on this occasion. John Kasich has been seduced on his way to the Rose Garden, and has banished himself from the scramble for the White House to — if he doesn’t compound his miscues — the second prize in the lottery and a comfortable stay in the vice-presidential Naval Observatory.

In London last week, Barack Obama showed us once again why he has been a disastrous president. Repaying the hard-pressed prime minister, David Cameron, for his improper importuning of the support of United States senators for the disgraceful Iranian nuclear-weapons agreement, the president gave the British a finger-wagging lecture on why they must submit to Brussels, accept German laws, pour money into European pockets, and receive unquestioningly the vast flotsam of wretched and desperate people unloosed on Europe by American, conspicuously Mr. Obama’s own, blunders in the Middle East.

The President completely missed the Clapham Omnibus. He said Britain must submit to being subsumed into Europe to retain any influence in Washington, and if it fails to vanish under the Euro-anesthetic, forfeiting the birthright of every Englishman for a thousand years, the United States, armed to the teeth with its mighty trade deficit, will banish it “to the back of the queue” as a trading partner. The European Union, which is largely an anti-American confection, though Nixon and Reagan were the only American presidents sufficiently perceptive to see this, must be allowed to consume and emasculate the greatest ally the United States has ever had — or the United States will punish it itself.

This too, has backfired. Britain has no illusions about the decline of its influence in the last 75 years. But it remains a great and a proud nation. It will not be treated by this departing and, in foreign-policy terms, singularly inept American president like an obstreperous child trying to defer its bedtime. Any of the remaining presidential candidates except Senator Sanders would be an improvement on the incumbent. None could be as transformative of America (to a semi-bankrupt laughing stock) as Mr. Obama has been.

This creates a challenge and an opportunity for his successor. Donald Trump marked the occasion by announcing that he will bring back to the White House the bust of Winston Churchill that Mr. Obama finally manfully acknowledged that he had had removed. The United States has revived quickly from graver political influenzas than the one that now afflicts it, but not so often that anyone should be complacent about it.

Cbletters@gmail.com. From the National Review.