Paul Krugman asks in this column how the Republican Party could have allowed a con artist like Donald Trump to take over the party and become its nominee. Why didn’t other Republicans expose the scams and frauds that have generated profits for Trump? Why were reporters able to discover what was in plain sight but not the other candidates?

He says it is because a party that worships profit and insists that government is the problem is wide open for frauds, profiteers, and grifters. “Greed is good” is not a maxim to live by.

He writes:

Consider this: Even as the newspapers are filled with stories of defrauded students and stiffed contractors, Republicans in Congress are going all-out in efforts to repeal the so-called “fiduciary rule” for retirement advisers, a new rule requiring that they serve the interests of their clients, and not receive kickbacks for steering them into bad investments. Paul Ryan, the speaker of the House, has even made repealing that rule part of his “anti-poverty plan.” So the G.O.P. is in effect defending the right of the financial industry to mislead its customers, which makes it hard to attack the likes of Donald Trump.

Finally, the con job that lies at the heart of so much Republican politics makes it hard to go after other, more commercial cons. It’s interesting to note that Marco Rubio actually did try to make Trump University an issue, but he did it too late, after he had already made himself a laughingstock with his broken-record routine. And here’s the thing: The groove Mr. Rubio got stuck in — innuendo that the president is deliberately weakening America — was a typical example of the political snake-oil the right sells along with free money and three-minute cures for high blood pressure.

The point is that Mr. Rubio was just as much a con artist as Mr. Trump – just not as good at it, which is why, under pressure, he kept repeating the same memorized words. So he, like all the G.O.P. contenders, didn’t have what it would have taken to make Mr. Trump’s grifting an issue. But at least so far it appears that Hillary Clinton and her allies won’t have the same problem.

In the months ahead Republicans will claim that there are equivalent scandals on the Democratic side, but nothing they’ve managed to come up with rises remotely to the level of even one of the many Trump scams in the news. They’ll also claim that Mr. Trump doesn’t reflect their party’s values. But the truth is that in a very deep sense he does. And that’s why they couldn’t stop him.