It turns out Toni Morrison’s famous line about Bill Clinton as “our first black president” was just a bon mot. If the Clintons took it as a sign of blacks’ unconditional fealty, they were mistaken.A new Washington Post-ABC News poll shows black Democrats nationwide now support Barack Obama over Hillary Clinton for the presidential nomination nearly 2-1. This striking reversal — a month ago, Clinton held a big lead among blacks — is perhaps why race has suddenly become such a hot issue in a campaign that previously had dodged the subject.It was never realistic to think race — or gender, for that matter — would stay out of a contest starring the first woman and the first black with realistic hopes of becoming president. From the Democrats’ point of view, it’s probably better to hash all this out now rather than wait until the general election campaign, when the Republican Swift-boat machine would set the parameters and tone for the discussion.Still, it’s surprising the Clinton campaign has been so aggressive in keeping the race issue alive. On “Meet the Press,” Clinton didn’t just seek to explain her remarks about the Rev. Martin Luther King Jr.’s role in landmark civil rights legislation (she said it took a president to bring about real action) or Bill’s “fairy tale” crack about Obama’s record on the Iraq War (which some blacks took as a dismissal of Obama’s candidacy as mere fantasy). Instead, she went on the attack, accusing the Obama campaign of “deliberately distorting” her words in a way that was “unfair and unwarranted.”That seemed a curious tactic to employ just two weeks before the South Carolina Democratic primary, in which blacks are expected to cast about half the total vote. It seemed especially curious after the most powerful black politician in the state, House Majority Whip James Clyburn, indicated he was so “bothered” by the Clintons’ remarks he might rethink his decision not to endorse before the primary.With most polls showing Clinton well behind in South Carolina, it was unclear how this approach would do anything but put her further behind.The charitable explanation would be that the Clintons are, in terms of their political position, simply disoriented. They are accustomed to Bill Clinton’s campaigns, in which black support was pretty much assumed. Backing for Hillary Clinton from prominent friends and allies such as Andrew Young, Rep. John Lewis, D-Ga., Vernon Jordan, Magic Johnson, Quincy Jones and others didn’t manage to keep Obama out of the race — and, according to the polls, won’t keep black voters from supporting him. It would be understandable if the Clintons were frustrated at seeing such an important Democratic constituency lured away, and if they were doubly frustrated at the difficulty of finding a way to criticize Obama without further alienating blacks.This is politics, however, which means less charitable explanations have to be considered as well.Race is just one of the fights the Clinton campaign is pressing with Obama at the moment; the other is an attempt to discredit Obama’s opposition to the war. It could be that the idea is to engage Obama in so much tit-for-tat combat that his image as a new kind of post-partisan politician is tarnished.Or the strategy could be more subtle. I can’t help but recall a certain piece of history.In 1992, when Bill Clinton was running for president, a controversial hip-hop artist named Sister Souljah made an ugly comment about the Los Angeles riots: “If black people kill black people every day, why not have a week and kill white people?” Candidate Clinton highlighted the remark in a speech to the Rev. Jesse Jackson’s Rainbow Coalition, comparing Souljah to Ku Klux Klan member David Duke. The episode demonstrated that Clinton was not only tough on lawlessness but also willing to challenge “special interests” — in this case, black activists.The Clintons are reading the polls, too; they might well be resigned to the possibility that most black Democrats will vote for Obama. This would mean South Carolina is probably already lost, and the campaign’s focus now has to be on Florida and the many states whose delegates are up for grabs on “Tsunami Tuesday.”Is it possible that accusing Obama and his campaign of playing the race card might create doubt in the minds of the moderate, independent white voters who now seem so enamored of the young black senator? Might that be the idea?Yes, that’s a cynical view. But history is history.Send Eugene Robinson e-mail at email@example.com.