Perhaps the dirtiest little secret of the Democrats’ coalition is the absolute conflict of interest between the open borders/Hispanic wing of the party, viewed as the future of the party, and the black faction, whose reliable high turnout is essential to the party’s current election prospects.  To anyone who understands supply and demand, the influx of millions of low-skilled immigrants obviously has damaged the market for the labor of low-skilled blacks, who also number in the millions.  This is the principal reason for wage stagnation in the lower half of the income distribution.

However, this is a matter of abstraction, and with the connivance of bought-and-paid-for black leadership, from Jackson and Sharpton to the NAACP, rank-and-file blacks have been kept quiescent on the subject.

And then along comes Donald Trump, a celebrity from TV whose appeal includes large numbers of black fans, who appears with the family of Jamiel Shaw II, slain by an illegal immigrant.  Unlike labor market calculations, this is concrete, human, and easy to understand.  In the words of Mickey Kaus, one of the shrewdest observers of politics, "Jamiel Shaw (son killed by undoc gangbanger) should terrify Dems--threatens to open suppressed black/La Raza rift."

We shall see where Trump goes with this, but if he begins to bemoan the effects on blacks of untrammeled immigration, the Democrats will have a real problem on their hands.  They have been playing both sides of the street, avoiding the uncomfortable truth that they are sacrificing the interests of blacks in favor of the interests of open borders.  Without enthusiastic black turnout, they are dead in the water.