Donald Trump has insisted over the past two weeks that the judge overseeing the Trump University fraud case cannot act impartially because he is "Mexican" (later: "of Mexican heritage"). That insistence has been received poorly, including by formerly stalwart Trump allies such as Newt Gingrich.

On Sunday morning, Trump expanded his line of thinking outward. During an interview on CBS's "Face the Nation," Trump was asked whether a Muslim judge would similarly be incapable of treating him fairly.

His response? "It's possible, yes. Yeah. That would be possible, absolutely."

Let's set aside the fact that Article VI of the Constitution prohibits the sort of religious test that Trump would apparently like to apply to those who sit in judgment of him. And let us also set aside that, in 1998, lawyers who questioned the fitness of a judge based on his ethnicity were reprimanded severely, to the point that they were mandated to inform future judges in the district of their botched challenge.

Let us instead try to isolate which judges Donald Trump would like to bar from overseeing any future legal disputes involving his get-others-rich-quick schemes. We already know that Trump could reject anyone who is Muslim, "Mexican" or "of Mexican heritage." (Those are in quotes because "Mexican," in this instance, doesn't actually mean Mexican: The judge in the Trump University case is from Indiana.)

CNN reporter Jake Tapper asked Republican presidential candidate Donald Trump if his judge attack was racist, then followed up 23 times. (Thomas Johnson/The Washington Post)

The benchmark for exclusion isn't solely membership in a group that Trump has criticized and/or sought sanction against. It's membership in a group that Trump might be able to argue could view him negatively. After all, he regularly insists that Hispanics love him, but he, for some reason, assumes Gonzalo Curiel doesn't. He assumes Muslims would judge him harshly but tells the world that Muhammad Ali's rebuke of his ban on Muslim entry into the United States wasn't about him.

With that dichotomy in mind, logic would suggest that Trump could probably also exclude as unfit:

Judges from the Democratic Party. No Democratic judges, obviously, given both that Democrats clearly oppose his candidacy and that he has, in the past, described members of the party as having given rise to the Islamic State militant group.

Judges who are immigrants. Trump's broadly skeptical view of immigration of all stripes drives much of his campaign rhetoric, from the wall on the Mexican border (which doesn't target only Mexican immigrants, of course) to his ban on Muslims. His policy proposals would add broad new constraints to entering the country, legally or illegally.

Judges who are women. Trump's contentious history with women — a history that he has gone to great lengths to smooth over — is well documented. The New York Times collected a series of quotes that might indicate why a female judge would, in Trump's eyes, be biased against him.

Judges who are black. Trump twice this weekend attempted to highlight support from black voters. He first pointed out a black man in the crowd at a rally, though that man wasn't a Trump supporter. He then tweeted an image of a black family that supported him — but the image was a news photo from an unrelated event. But that aside, his past comments about black people, legal fights surrounding his company's renting practices and recurring overlap with racists on social media all offer more than enough reason for Trump to assume that a black judge would treat him unfairly.

Judges with physical disabilities. Trump's now-infamous imitation of New York Times reporter Serge Kovaleski speaks for itself.

So what's left? A white* male Republican judge. The good news for Trump, of course, is that there are plenty of judges who fall into that category. In 2013, the Federal Judiciary Center determined that only 39 percent of federal judges were women and only 37 percent weren't white. Figure about half of the 874 federal judges were appointed by Republicans, and that's a pretty big pool from which to choose.

Until Trump comes up with another reason to suggest that the judge is biased against him.

* This originally read "white or Asian," but then a colleague reminded me of the time that Trump offered his imitation of an English-speaking Chinese person, so probably safer not to count on a judge of Chinese descent.