If Donald Trump somehow falls three delegates short of reaching the magic 1,237 delegates needed for the Republican nomination, he may be haunted by an obscure outcome from the primary voting in Illinois on Tuesday. There’s clear evidence that Trump supporters in Illinois gave fewer votes to Trump-pledged delegate candidates who have minority or foreign-sounding names like “Sadiq,” “Fakroddin” and “Uribe,” potentially costing him three of the state’s 69 delegates.

This pattern appears to be a phenomenon unique to Trump’s supporters.

Illinois Republicans hold a convoluted “loophole” primary: The statewide primary winner earns 15 delegates, but the state’s other 54 delegates are elected directly on the ballot, with three at stake in each of the state’s 18 congressional districts. Each campaign files slates of relatively unknown supporters to run for delegate slots, and each would-be delegate’s presidential preference is listed beside his or her name. As a result, the top presidential candidate in each congressional district usually claims all three of the district’s delegates.

Except on Tuesday, a handful of congressional districts split their delegates in ways that cast doubt on voters’ racial motivations. Did voters have genuine personal preferences for the mostly anonymous individuals running for these slots, or was it a case of “what’s in a name?”

A FiveThirtyEight analysis of the dozen highest vote differentials within district-level Trump slates reveals a startling pattern: In all 12 cases, the highest vote-getting candidate had a common, Anglo-sounding name. But a majority of the trailing candidates had first or last names most commonly associated with Asian, Hispanic or African-American heritages. Of the 54 Trump delegate candidates in the state, two of the three worst-trailing candidates were the only two Trump candidates with Middle Eastern-sounding names.

DISTRICT LEADING TRUMP DELEGATE VOTES TRAILING TRUMP DELEGATE VOTES DROP-OFF IL-13 Doug Hartmann 31,937 Raja Sadiq 24,103 -25% IL-16 Eric Miller 34,214 Michael Bissenbach 28,915 -16 IL-06 Paul Minch 35,435 Nabi Fakroddin 30,639 -14 IL-13 Doug Hartmann 31,937 Toni Gauen 28,337 -11 IL-02 James Devors 11,938 Taneequa Tolbert 10,615 -11 IL-17 Rich Nordstrom 24,697 Jim Uribe 22,036 -11 IL-01 Michael Burke 16,972 Christopher Hilliard 15,571 -8 IL-15 Philip Chapman 45,387 Sam Stratemeyer 41,642 -8 IL-01 Michael Burke 16,972 Antonio Alonso 15,576 -8 IL-18 Kent Gray 37,091 Sandra Yeh 34,344 -7 IL-15 Philip Chapman 45,387 Maria Hough 42,363 -7 IL-04 Kevin Jayne 5,797 Rolando Arellano 5,437 -6 Largest disparities within district-level Trump delegate slates Source: CBS Chicago

In the western Chicago suburbs, a Trump delegate candidate named Nabi Fakroddin received 14 percent fewer votes than a member of the same Trump slate named Paul Minch. In southern Illinois, a would-be Trump delegate named Raja Sadiq received an eye-popping 25 percent fewer votes than a slate-mate named Doug Hartmann. And in a rural western Illinois district, a losing Trump delegate named Jim Uribe received 11 percent fewer votes than one named Rich Nordstrom. In all three cases, the disparity appeared to cost Trump a delegate.

In an African-American majority district on Chicago’s South Side, a Trump delegate named Taneequa Tolbert received 11 percent fewer votes than a slate-mate named James Devors. And in a neighboring Chicago district, a Trump delegate named Antonio Alonso received 8 percent fewer votes than a slate-mate named Michael Burke. In these two instances, Trump still swept all three district-level delegates because no other candidate’s delegates came close.

Of the seven Trump delegate candidates with minority or foreign-sounding names, all seven were among the dozen worst-trailing Trump candidates in the state: Sadiq, Fakroddin, Tolbert, Alonso, Uribe, Sandra Yeh and Rolando Arellano. The 47 Trump delegate candidates with Anglo-sounding names tended to garner far more votes.

Not all cases of “split districts” appeared to involve candidates with foreign-sounding names. In some districts, there were significant vote differences between members of Ted Cruz’s and John Kasich’s slates that didn’t appear to have anything to do with racial or ethnic backgrounds. But Trump’s Illinois disparities were unique to his candidacy, and they lend credibility to the theory that racial resentment is commonplace among his supporters.

Ironically, in the case of Illinois, such resentment also appears to have played to Trump’s own detriment.