Formally, the House of Representatives is holding an inquiry into the question of whether Donald Trump should be impeached. In reality, we’ve known the answer to that question for a long time. In a different era, when both parties believed in the Constitution, Trump’s abuse of his position for personal gain would have led to his removal from office long ago.

No, what we’re actually witnessing is a test of the depths to which the Republican Party will sink. How much corruption, how much collusion with foreign powers and betrayal of the national interest will that party’s elected representatives stand for?

And the result of that test seems increasingly clear: There is no bottom. The inquiry hasn’t found a smoking gun; it has found what amounts to a smoking battery of artillery. Yet almost no partisan Republicans have turned on Trump and his high-crimes-and-misdemeanors collaborators. Why not?

The answer gets to the heart of what’s wrong with modern American politics: The GOP is now a thoroughly corrupt party. Trump is a symptom, not the disease, and our democracy will remain under dire threat even if and when he’s gone.

The usual explanation you hear for GOP acquiescence in Trumpian malfeasance is that elected Republicans fear being defeated in a primary if they show any hint of wavering. And that’s certainly an important part of the story.

Republicans haven’t forgotten what happened in 2014, when David Brat, a Tea Party insurgent, ousted Eric Cantor, at the time the House majority leader. Cantor was a hard-line conservative, but mild-mannered in affect, and perceived as soft on immigration. The lesson was that the GOP base demands red meat, and these days that means supporting Trump no matter what.

But electoral fears aren’t the only thing keeping Republicans in line.

On one side, I don’t think most observers realize, even now, the extent to which many Republicans view their domestic opponents not as fellow citizens but as enemies with no legitimate right to govern.

Attorney General William Barr says that progressives are “militant secularists” out to “destroy the traditional moral order.” If that’s how you see the world, you’ll support anything — up to and including soliciting and/or extorting intervention by foreign powers in U.S. elections — that helps defeat those progressives.

On the other side, it’s notable that with few exceptions even Republicans who are leaving or have left office still refuse to criticize Trump. There has been a wave of Republicans announcing retirements from the House, and there’s little question that some of these politicians are leaving because they’re disgusted with serving this administration. Yet almost none have said so explicitly, even though they won’t be facing any more primaries. What keeps them in line?

The answer is, follow the money.

What, after all, do retired officials do for a living? Many become lobbyists, and in an era of extreme polarization that means lobbying their own party. Being honest about why you quit would be bad for future business.

Beyond that, the modern U.S. right contains many institutions — Fox News and other media, right-wing think tanks, and others — that offer sinecures to former officials. However, this “wing-nut welfare” — which has no counterpart on the left — is available only to those who continue to toe the line.

Earlier I mentioned David Brat, who ousted Eric Cantor. As it happens, Brat himself was defeated in last year’s Democratic landslide. So what’s he doing now? He’s dean of the business school at Jerry Falwell Jr.’s Liberty University.

So financial incentives keep even retiring Republicans in line. And the exceptions prove the rule.

As far as I can tell, Gordon Sondland, who is ambassador to the European Union — but surely not for long — was the first political appointee, as opposed to professional civil servant, to attest to the Trump administration’s abuse of power in Ukraine. A key point about Sondland, however, is that he’s a rich man who doesn’t need wing-nut welfare.

He’ll live comfortably in retirement as long as he doesn’t go to jail. So his incentives were very different from those facing most GOP figures.

So are all Republicans corruptly subservient to Trump? No, there are some honorable Never Trumpers, including many of the foreign-policy neocons like William Kristol. Some of us will never forgive this group for misleading us into war, but it turns out that they really do have principles and deserve recognition for their current political courage.

But the modern GOP as a whole is overwhelmingly fanatical, corrupt or both. Anyone imagining that the mountainous evidence of Trump’s malfeasance will lead to a moral awakening, or that Republicans will return to democratic political norms once Trump is gone, is living in a fantasy world. Even catastrophic electoral defeat next year probably wouldn’t do much to change Republican behavior.

The big question is whether America as we know it can long endure when one of its two major parties has effectively rejected the principles on which our nation was built.

Paul Krugman | The New York Times (CREDIT: Fred R. Conrad)

Paul Krugman, Ph.D., winner of the Nobel Memorial Prize in Economics, is an Op-Ed columnist for The New York Times.