Sen. Hillary Clinton has disgracefully pursued a disturbing strategy of racial opportunism.

Since early March, when Sen. Barack Obama racked up victory after victory in states that were, in some instances, overwhelmingly white and, in others, significantly black and Latino, the strategy of the Clinton campaign has whitened day by day.

Despite support from some key black politicians and a black campaign manager, the Clinton operation determined that low-income, lower-educated, non-urban whites were worth pandering to and that black voters were worth ignoring.

There were clearly white supporters of Clinton in Kentucky and West Virginia who stated strong and unambiguous racism toward Obama. Rather than repudiate these voters, Clinton silently clung to them.

Clinton’s strategy is a disaster for the general election.

The reality is that Clinton cannot win independents and moderate Republicans, and her support is concentrated in a narrow region of white and perhaps Latino Democratic voters.

Whatever black support she and Bill Clinton once enjoyed and felt entitled to — she led by as much as 57-33 percent over Obama in December 2007 — has vanished, perhaps permanently.

And there is not a single party official with a brain who does not know that if Clinton somehow manages to wrestle the nomination away from Obama through a combination of rule manipulation, superdelegate chicanery and race-baiting, the party will suffer a black-and-white withdrawal and November beat-down of historic and long-lasting proportions.

The Democrats have to be very careful not to be suckered into the Clintons’ argument that the only winning strategy in the fall is the pursuit of white lower-income voters. Clinton supporter Paul Begala, for instance, belittled Obama’s based by saying that it consisted of “eggheads and African-Americans.”

In fact, the party can win by going to (and expanding) its natural base, pulling in significant independent voters and carving off enough dissatisfied Republican moderates.

With Obama, there are more states in play, thus forcing the Republicans to more widely disperse their resources. And he generates a black turnout that will perhaps be the largest the country has ever seen, a preview of which has already contributed decisively to Democratic victories in Louisiana and Mississippi in recent special elections.

Finally, the grim reference to the assassination of Robert Kennedy, whatever the motivation, and in the context of the very real death threats that Obama has faced, reveals in Clinton the triumph of calculation over sensitivity.

It is unfortunate that the Clinton campaign has succumbed to blind ambition and turned a history-making election into a history-repeating voyage of racial ugliness and accommodation.

They had a choice, and they took the low road.

Clarence Lusane is an associate professor at American University and author of many books, including, most recently, “Colin Powell-Condoleezza Rice: Foreign Policy, Race and the New American Century.” He can be reached at pmproj [at] progressive [dot] org.