White college graduates have emerged from the last two decades of elections as an increasingly large and cohesive political bloc -- and one that poses problems for both political parties. Back in the pre-COVID-19 era, their numbers augmented by recent products of woke campuses, they seemed to be the dominant force in the race for the Democratic presidential nomination. They flitted from one candidate to the next, tilting toward Sen. Kamala Harris after she whacked Joe Biden for opposing school busing in the 1970s, then luxuriating in Sen. Elizabeth Warren's stentorian assurances that, on every issue, she had "a plan...