With the election of Obama, many Americans believed that racial polarization in the country was over. White Americans in particular assumed that Obama's election would be a transformative moment, effectively capping America's centuries-long odyssey toward racial equality.

Unfortunately, this has not been the case. Over the past decade, racial groups have become more polarized, not less. A simple example will suffice. A personal friend, a white man who teaches at an inner-city school in Los Angeles County with an almost entirely Hispanic population, polled his students shortly before the 2008 election regarding their parents' presidential preferences. Every hand in the classroom went up for Obama. After class, my friend approached one of the students. "Why are your parents voting for Obama?” he asked a 10-year-old Hispanic girl. She answered him in four words: "Because he's not white.”

"Because he's not white” has become the rallying cry for racial minorities all across the country. There are 24 members of the Congressional Hispanic Caucus. Twenty-three are Democrats, and one is an independent. Leaving aside U.S. Sen. Ken Salazar, D-Colo., and two members of Congress who represent no district, the Hispanic population in the districts they represent averages 59.23 percent. That means that concentrated pockets of Hispanics elect Hispanics.

The same is true for the Congressional Black Caucus. There are currently 44 members of the Congressional Black Caucus; all are Democrats. Leaving aside Senator Roland Burris, D-Ill., and two nonvoting, at-large members of Congress, the black population in the districts they represent averages 48.47 percent. That means concentrated pockets of blacks elect blacks.

The same is largely true of whites, of course. The difference is that whites elect members of both parties -- racial identity is not bound up in political identity. For the Hispanic and black communities, however, racial and socioeconomic identity increasingly mean allegiance to one party: the Democratic Party. Thus, when Miguel Estrada is grilled by Democrats, no one worries about the electoral ramifications for the Democrats among Hispanics, yet when Sotomayor is nominated, critics worry that Republican criticism will drive away Hispanics. The same holds true for the black community: When Supreme Court Justice Clarence Thomas is raked over the coals by Democrats, no one worries that blacks will run from the Democratic Party; when Barack Obama is criticized by Republicans, however, the press declares that Republicans will lose the black vote forever.

The implications of the racial separation of our republic are supremely dangerous. It seems that racial groups more and more often vote along tribal lines; multiethnic democracy now means racial re-segregation, at least in terms of electoral politics. Small-R republicanism relies on the willingness of individuals to discern and vote for the politicians with whom they agree, not the politicians with whom they share a skin color, racial heritage, and economic background.

Barack Obama's candidacy was supposed to usher us into a post-racial America. It seems that his election, and his continuing exploitation of racial differences through nominations like Sotomayor's, has only deepened the racial divides.