At the risk of invoking an overused word, this is an unprecedented time in American politics — not just because we have never had a president as reckless as Donald Trump, but also because we have never had an impeachment inquiry this close to a presidential election in the television era.

Politics is now literally on a split screen. Democratic presidential candidates jostle one another over health care, corporate power, climate change, inequality and much else as the House Intelligence Committee hears from career civil servants about the Republican incumbent’s effort to corrupt the very election these candidates are contesting.

Trump faces impeachment because of well-substantiated charges that the “favor” he asked of Ukraine’s president was to announce an investigation that would undermine one of those candidates, former vice president Joe Biden, who happens to be polling best in states most likely to swing the 2020 outcome.

Although Trump’s specific effort ultimately failed, he has already succeeded in his larger mission. Most informed voters now know that Biden’s son Hunter worked for a company that did business in Ukraine while Joe Biden was vice president. It is a classic Trumpian operation: Sow doubts about an opponent, dirty her or him up, and let the media — yes, that “corrupt liberal media” that Trump and his apologists love to denounce — do the rest.

The collateral human damage of Trump’s immorality was brought home during Friday’s testimony from Marie Yovanovitch, the former U.S. ambassador to Ukraine. She resisted Trump’s use of American power on behalf of his own political interests and was thus removed by the president, at the instigation of corrupt elements in Ukraine.

The 33-year State Department veteran not only lost her post, but now faces a separate smear campaign. Trump’s tweets denigrating her public service while she testified led committee Chairman Adam B. Schiff (D-Calif.) to declare that “some of us here take witness intimidation very, very ­seriously.”

The shameful lack of decency from the man in the Oval Office would have been shocking from any other president, and House Speaker Nancy Pelosi suggested Sunday on CBS News’ “Face the Nation” that the tweet reflected how unsuited Trump is for the presidency altogether. “I think part of it is his own insecurity as an impostor,” she said. “I think he knows full well that he’s in that office way over his head.”

Now, move to the other screen. Ten Democratic presidential candidates will debate on Wednesday in Atlanta. Absent will be former Massachusetts governor Deval Patrick, who joined the race last week, and former New York mayor Mike Bloomberg, who is flirting with entering. The odds against such latecomers are overwhelming. That they believe they have any chance at all reflects more than their ambition. They’re also spurred on by the Trump-induced chaos and the widespread sense that the nomination contest is in a state of flux.

Biden has been hurt by his own missteps and Trump’s efforts to besmirch him. But he still leads in national polls, and hangs on to his support among older voters, white and African American alike. He can also claim the risks the president has taken to undermine him as evidence of his electoral strength. Weekend polls showed South Bend, Ind., Mayor Pete Buttigieg surging in Iowa, which will vote first in February. He can count on being the target of attacks from just about everyone else this week.

Sen. Elizabeth Warren (D-Mass.) has had the best year of anyone, but her embrace of Medicare-for-all has led to the first serious challenges to her seemingly inexorable rise.

She sent a strong signal on Friday that she understood the water her campaign was taking on. By issuing a plan calling for a gradual transition to a new health-care system and emphasizing that she would begin her term by strengthening Obamacare with a public option and regulatory actions, she moved herself closer to Biden and Buttigieg on the issue. This is a much safer position for a general election campaign, but it will be seen as a retreat by supporters of Sen. Bernie Sanders (I-Vt.), Medicare-for-all’s original champion, who has enjoyed a resurgence in the polls in recent weeks.

At one level, it’s a sign of the vitality of American politics that even as impeachment moves forward, at least one party is grappling with problems being left untended in the mayhem Trump has let loose.

Nonetheless, these candidates must remember the immediate priority of what’s happening on Screen One. The principal task between now and February is to help the country come to judgment about the president’s abuse of power and the dangers he poses to our republic.

Plans for health care and the economy matter enormously for the future, as Warren’s midcourse corrections demonstrate. But right now is the best opportunity these Democrats will have to show who is best positioned to prosecute the moral case against Donald Trump.

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