President Trump and Senator Vance will have the wind at their backs as, from Milwaukee, they fan out to sell the new Republican Party. The nominee is — for the moment — up five points in the polls against an incumbent who is too old and tuckered out to run, let alone serve. They will campaign to dismantle the Blue Wall, and to bring working Americans of the Rust Belt into the Republican Party. It is an exciting moment.

Who would have thought — back on, say, January 7, 2021 —  that  this is where President Trump would be four years hence? It was hard to see then, as the events of January 6 began to sink in, that he had any future in politics. Yet here he is, having powered his way to the nomination through the Republican primaries and a convention of unified members of the GOP, many of them new arrivals to the cause.

What accounts for this turnaround? One would have to start, we’d reckon, with Trump’s own remarkable fortitude, energy, and optimism. He’s clearly a force of nature, something that has never been clearer than in his seasons of adversity. Then there’s the sense among millions of Americans who voted for Trump — or wished they had — that his first term, to which he was elected in 2016, had been stolen by the Democrats.

By which we mean the refusal of so many Democrats to accept the outcome of the 2016 election and to grant the 45th president the victory he’d won. We refer to the leaks from the deep state, the barrage of lawsuits over nearly every policy, the accusations of collusion with the Russians that failed to pass muster with even a special counsel, and the hostility and intolerance of the press and the bien pensant salons of American liberalism.

Once President Biden acceded, the Democrats made a terrible mistake. They cast aside the promises of unity and normalcy and launched against Trump a campaign of lawfare calculated to destroy his ability to challenge Mr. Biden in 2024. A Democratic prosecutor in Georgia launched a sprawling racketeering case against the president and allies. Felony charges in the Stormy Daniels case were confected out of misdemeanors against him in New York.

Most of all, it was the politicization of the Justice Department that staggered Americans. What are they to make of the fact that the appointment of a special prosecutor to go after Trump happened only after — two days after — Trump announced he would run again? What are Americans to conclude other than that the effort to use federal criminal law against him was political at birth? That’s more serious than anything laid against Trump in court.

On top of all that comes the failure — and mendacity — of the Biden administration. This hit the big screen with the surrender of Afghanistan. Then the Senate’s brainstorm to pass a vast spending bill under the rubric of “inflation reduction.” Earth to Senator Schumer, Americans are not dumb. The administration has refused to accept rulings of the Supreme Court on everything from guns to abortion to student loan forgiveness.

No wonder the Trump-Vance ticket has the wind at its back. It would have been one thing had any of Mr. Biden’s dodges been successful. Americans, though, can see for themselves that they are not only not better off than they were four years ago but they’re worse off. Not that the election is a done-deal. Trump has the capacity to lose track of his own story, as he did last night in his stemwinder, which began well but became the longest acceptance speech ever in America.

A big uncertainty lies with the Democrats. Reports out of Delaware,  suggest the incumbent president is teetering toward standing down, and there is at least a chance — if only a chance — that a new and younger candidate could electrify the party convention at Chicago the way Senator Vance energized the GOP. President Trump would then have to demonstrate that he is not yesterday’s man. He certainly made a start in Milwaukee.