After the extraordinary series of leaks over the past few days, it's obvious Attorney General William Barr intentionally or unintentionally poisoned the rollout of Robert Mueller's comprehensive report on the Trump campaign's ties to Russia during the 2016 election.

It's hard to imagine the report will do anything but back up Barr's assertion that Mueller exonerated President Trump on the narrow but absolutely crucial matter of whether his campaign actively colluded with Russia to prevail against Hillary Clinton. But on other vitally important issues — Did the president or anyone else in the campaign or administration obstruct justice? Did members of the campaign attempt to collude with Russia while failing in their aims? Was the campaign inadvertently manipulated by Russian operatives seeking to interfere with the election? — we know nothing definitive yet.

Learning the answers to these questions is important, of course. But in the long run, just as important may be the way we learn the answers. If Barr had taken a few more days to scrub the full report before releasing it, or simply released the already sanitized summaries of the report's conclusions we now know Mueller included with it, everyone would have been capable of evaluating those conclusions independently. Each side would have spun the findings for its advantage. But the evidence would be there for all to judge.

Instead, Barr kept the report and the summaries secret, pronounced the president exonerated on one key element of the investigation while remaining silent about the others, and left it to members of Mueller's team to start leaking about their displeasure at Barr's interpolation of their conclusion 10 days later.

Why does this difference matter? Because appearances matter in politics. Mueller and his team understand this very well. It's why, despite the constant barrage of abuse the president and his minions directed their way for the better part of two years, they never leaked a thing, never retaliated, never spoke to journalists on or off the record to hint at their preliminary findings or potential wrongdoing on the part of the president or his campaign. They knew that their work was delicate, that they were conducting it in an environment of scalding-hot partisanship, and therefore that they needed to display scrupulous professionalism and fairness. This doesn't make Mueller an angel. It makes him someone who understands politics.

Trump and leading members of his party think they understand politics too. Indeed, one way to think about the turbulence of the present moment in American public life is to view it as a contest between competing visions of how politics works. Mueller is the traditionalist, striving to uphold norms of propriety, even-handedness, and institutional impartiality. One arm of the government (the special counsel's office) can investigate another (the president and those around him) fairly if those conducting the investigation remain on guard against bias and scrupulously follow the rules.

Trump and ever-growing numbers of Republicans take another view. For them, everything is invariably transactional and zero-sum. There is no rising above partisanship. There are winners and losers, friends and enemies, and nothing in between. Displays of high-mindedness always conceal baser motives. No one is above the fray. Nothing is impartial. Believing otherwise is for saps, suckers, and chumps.

By pronouncing the president exonerated without providing further information about the content and conclusions of the report, Barr handed Trump the power to establish a baseline of interpretation. The Mueller report fully vindicated his denials of any wrongdoing at all. "No collusion!" Now any muddying of that position, whether it comes from leaks by disgruntled members of Mueller's team or the published report itself, will have the air of revisionist history about it. Now Trump and his defenders will be able to cast that shift as politically motivated. Once again the effort to rise above factionalism will be portrayed as illusory. After all, Barr told us the report exonerated the president.

This was entirely preventable — if only Barr had acted with greater care and caution, and with greater concern about his own potential contribution to the further degradation of our already rapidly decaying political norms.

That doesn't mean that Trumpworld would have accepted a mixed or negative report without considerable nastiness (even if it fell short of recommending prosecution for collusion with a foreign power). The reaction to criticism from the special counsel was always going to be severe. But if Trump's own Republican attorney general had formed a united front with the Republican special counsel in carefully explaining to the American people that, although Trump's presidential campaign didn't actively collude with Russia, it did do numerous things that were deeply worrying and far beyond the bounds of normal and acceptable behavior, that could have done an awful lot of good.

It would have shown that it's still possible for us to govern ourselves fairly — to uphold high standards for both political officeholders and those who investigate their alleged wrongdoings. Instead, we have just the latest incident in the sleazefest that American politics has become.

And it will only get worse if Barr continues to stall and frustrated members of Mueller's team feel compelled to start leaking the content of the report (which they so far haven't done). This would ensure that, no matter what's in it, the report and its conclusions are spun by Trump and his defenders as a hopelessly tainted partisan hit job by the president's enemies — and that people will be inclined to believe them.

Appearances matter in politics. And thanks to William Barr, things are looking pretty bad.