In July, President Trump withheld $400 million in military aid for "at least a week" prior to a phone call with Ukrainian President Volodymyr Zelensky, in which Trump pressured Zelensky to investigate Joe Biden's son, The Washington Post reports.

It is beyond obvious what this represents. Trump was attempting to subvert the 2020 election by using his powers of office to gin up a political prosecution of his top opponent's family.

To briefly recap, some years ago Hunter Biden had a sleazy influence-peddling job sitting on the board of a Ukrainian energy company. Then-Vice President Joe Biden was at the time leading an anti-corruption pressure campaign, trying to convince the Ukrainian government to fire its top prosecutor on behalf of the Obama administration and several European countries. The prosecutor was by all accounts corrupt, and he was fired, but Biden still had a huge conflict of interest in the form of his son.

That certainly doesn't look good, and it doesn't speak well of either Biden. But as Louis Jacobson carefully outlines at Politifact, there was no evidence Biden's decision hinged on trying to protect his son, and neither is it clear Hunter Biden's firm was even under investigation or that the change helped the firm. Multiple European countries with no connection to Biden were behind the push as well.

More importantly, the details of the Biden story are beside the point. If Trump was seriously concerned about corruption there is a vast American law enforcement apparatus he might use for that purpose. As Talking Points Memo's Josh Marshall writes, he was almost certainly "demanding that Ukraine manufacture damaging and false information about Joe Biden, either directly or via his son."

Conversely, Trump is about the least credible advocate for clean government it is possible to imagine. The man is the most nakedly corrupt president in American history — operating a giant business empire that gives him conflicts of interest across the world, directly stuffing foreign bribes and the White House budget into his own pockets in flagrant violation of the Constitution, obstructing justice, and on and on. Undoubtedly what makes Trump maddest about the Biden story is that it wasn't his son collecting $50,000 per month for some no-show job.

All this is quite similar to how Jair Bolsonaro won the presidency of Brazil. As documents recently revealed by Glenn Greenwald, Leandro Demori, and Betsy Reed at The Intercept show, before the recent election Bolsonaro's top opponent Luiz Inácio Lula da Silva was put in jail through a crooked trial where Judge Sérgio Moro (now Bolsonaro's powerful minister of justice) secretly worked hand-in-glove with the prosecutors to rig the entire thing.

Lula probably actually was guilty of some minor corruption (if for no other reason that he is a top-level Brazilian politician, and that's how business has been done there for decades). But that does not excuse a rigged prosecution whose purpose was to steal a Brazilian election.

In my view Joe Biden is a wildly inappropriate nominee for the 2020 primary for a variety of reasons, and he is more vulnerable due to his failson. But it's probably wise to assume that any other nominee would face similar political harassment. Pretexts could be found — Kamala Harris's failure to prosecute OneWest as California Attorney General, Jane Sanders' botched management of a small college, Warren's native American heritage thing — or failing that, invented. Trump is simply not going to allow a free and fair election in 2020 if he can possibly help it. And as president, he has a lot of power to do so.

And that is why the recent stampede among House Democrats to impeach Trump is such a welcome development. The Senate almost certainly will not vote to convict, or perhaps even hold a trial. But if House Speaker Nancy Pelosi and the rest of the party want to preserve American democracy, they are going to have to press their oversight powers to the utmost. The American people might not be able to do her job for her — that is, getting rid of Trump — if the 2020 election will be in some way rigged.

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