Impeachment isn't about the law. It's about politics.

Those feeling a little giddy about the astonishing revelations in Special Counsel Robert Mueller's investigation of Russian collusion in the 2016 election would be well advised to remember that.

Trump's campaign chairman Paul Manafort and his associate Richard Gates could be found guilty of every charge that has been brought against them, including "conspiracy against the United States"; Trump campaign policy adviser George Papadopoulos could testify that numerous senior members of the campaign, including the president himself, were aware of efforts to collude with Russian intelligence services to defeat Hillary Clinton; this testimony could lead to a slew of indictments and convictions of people in and around the Trump administration; the president could attempt to prevent things from getting this far by making an effort to fire Mueller — all of this (and more) could happen and President Trump could still remain in office. That's because it's generally accepted that sitting presidents cannot be prosecuted, and removing a president from office requires a series of actions by Congress that the current Congress shows no sign at all of undertaking.

Not only have leading Republicans in the House and Senate (at least those who aren't fighting brain cancer or about to retire) showed reluctance to move against the president, they have begun to do the opposite — that is, to work with influential right-leaning media outlets to discredit Mueller and his investigation.

Far from gearing up to remove the president, Republicans are acting to protect him. Why? Two reasons: First, because Republican donors want their tax cut; second, because President Trump remains quite popular with the Republican electorate — popular enough that elected officials are terrified of opposing him.

Of course it's possible that Mueller's investigation will turn up evidence so damning that the tide of Republican public opinion will finally turn against the president. In that case, impeachment might become a live possibility.

The problem is that Republican efforts to defend the president (emanating from the White House, Congress, Fox News, and other right-wing media outlets) are designed to keep that from ever happening — not by putting forth a cogent, fact-based defense of the president, but by constructing an alternative reality in which any and all charges against him can be dismissed as a product of flagrant partisanship and corruption on the part of his political enemies.

In this alternative reality, Robert Mueller is a partisan hack pushing a Democratic Party agenda, and it was Hillary Clinton and her campaign that colluded with Russia, not the Trump campaign. It doesn't matter, and will never matter, that neither assertion is true. All that Republicans need to do is raise enough doubts about the fairness of the investigation in the minds of voters that they conclude there's no possible way to ever determine to truth. "Yeah, Mueller's charges sound bad, but how can we trust him? He's just as bad as James Comey. They're all dirty. And anyway, what about Crooked Hillary and her allies?"

Once voters begin to think and say things like that, the battle has been won. The president has been rendered untouchable.

And that points to what might be the most significant form of collusion in the entire affair — not the Trump campaign's collusion with a hostile foreign power for the purpose of winning a presidential election, but the collusion between Republican voters and elected office-holders for the purpose of protecting the president and the party's political power in Washington.

Republican politicians and freelance propaganda ministers feed the voters lies, the voters happily swallow them, and then the politicians shrug their shoulders, claiming to lack the public support to act against the lawless president. It's the kind of self-reinforcing political corruption that forms the basis for authoritarian governments around the world.

And it may be the only way President Trump can survive the maelstrom that now threatens to consume him.