Years from now, when historians strain to describe the tumultuous Age of Trump, they may discover that all the tensions of that fevered era could be captured in a few hours this week.

For in that brief but extraordinarily revelatory period, the strains of the age – a president under legal attack, vital midterm congressional elections and a country riven by divisions so wide that Americans’ world views have little in common – were on full display. And in the guilty plea of his former fixer-lawyer, the conviction of his former campaign chairman for financial fraud and a thunderous performance in a political rally in West Virginia, the complexities and contradictions of contemporary American politics came into the sharpest focus yet.

In that West Virginia political appearance Tuesday evening – one of many the President is undertaking to preserve Republican control of Congress and frustrate Democratic efforts to impeach him – Mr. Trump ignored or dismissed the legal difficulties of Michael Cohen and Paul Manafort.

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But those legal difficulties – both men face prison sentences, and the Cohen guilty pleas directly implicated the President in illegal payments intended to affect the 2016 campaign – only raised the pressure on Mr. Trump and, in turn, only raised the stakes of November’s elections, when all 435 seats of the House of Representatives and 35 seats in the Senate are being contested.

In truth, the eight counts against Mr. Manafort, a classic Washington inside-operator who began as a conservative activist and ended as a grifter for dictators, had, as Mr. Trump said, ‘’nothing to do’’ with the President, though his critics were quick to ask why the leading Republican presidential candidate would invite such a figure to his inner circle. The Cohen guilty pleas present different, and far more serious, challenges for Mr. Trump.

It was not only that Mr. Cohen, in a Manhattan courtroom, acknowledged that his hush-money payments were intended to hide Mr. Trump’s extramarital affairs ‘’for the principal purpose of influencing the election.’’ It was also that Mr. Cohen asserted he made those payments on the orders of Mr. Trump, which implicates the President in violations of campaign-finance law.

It was not only the customary Trump critics who found the Cohen pleas remarkable – and darkly threatening. For hours on Tuesday, the website of Fox News, ordinarily an ardent supporter of the President, carried a headline with an ominous phrase from the Watergate period: "unindicted co-conspirator.’’ That legal term, applied to Richard Nixon, entered the popular lexicon after the Watergate grand jury employed it to describe the 37th president exactly two months before he resigned from office. Within hours, the phrase – part of the political commentary but not part of a judicial proceeding – was renewed for a 21st century audience.

In the Watergate episode, that finding tied Mr. Nixon to activities of his aides – ‘’an umbilical cord between him and us,’’ in the characterization of a defence attorney for others charged in the Watergate cover-up. The Trump case remains far from that, with the report of special counsel Robert Muellerstill in the future. The Manafort conviction, however, was an important test of the Mueller team’s ability to buck relentless presidential criticism and bring cases to trial.

Mr. Trump’s appearance in West Virginia, a state where he carried all 55 counties and defeated former Secretary of State Hillary Rodham Clinton by an astonishing margin of more than two-to-one, was coincidental but consequential.

West Virginia is one of the 10 states carried by Mr. Trump where Democrats are running for the Senate and a microcosm of the vast political change in the United States. Only 20 years before Mr. Trump defeated Mrs. Clinton by 42 percentage points, Bill Clinton defeated former Senator Robert Dole by 15 points. That 57-percentage-point swing in two decades is a measure of how voters once ardently loyal to the Democrats have migrated to Mr. Trump’s entreaties – on coal in West Virginia and other mining states and on immigrants in manufacturing and southern border states.

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Mr. Trump is in no imminent peril, but his political destiny and legacy will be shaped by the Mueller report and by November’s elections.

If the Democrats retake the House, and if Mr. Mueller issues a searing report, Mr. Trump could face impeachment hearings – a brutal experience that in the Nixon case led to his resignation before proceedings began and in the Bill Clinton case, based on his affair with a White House intern, led to a Senate trial that came short of convicting him and removing him from office.

Mr. Nixon’s fate was sealed when senior Republicans, including 1964 presidential nominee Senator Barry Goldwater of Arizona, told him he had lost his political support and pushed him to resign in August, 1974. Democrats hold out the hope that senior Republicans might perform the same task at the Trump White House, because even if the GOP loses control of the Senate, it would be immensely difficult for Trump critics to find the 67 votes against the President needed for impeachment. No president has been removed from office as a result of the impeachment process, though Andrew Johnson survived by a single vote in 1868.

More immediately, the President is not likely to be prosecuted on charges growing out of the Cohen pleas or any future court action. Though the Constitution does not specifically address the matter and the Supreme Court has never taken up the issue, legal experts generally agree that at worst, Mr. Trump could be indicted but not brought to trial until after he leaves office.

But before that, he faces 470 political trials this autumn. The President’s future, and the shape of American politics into the third decade of the 21st century, depend on the verdict of those political trials.