South Carolina was not a good litmus test for Obama.

The Clinton camp would like to brush off the weekend primary in South Carolina as not really that representative because so many African Americans voted. That in essence was what former president Bill Clinton was saying when he dismissed Illinois Sen. Barack Obama’s victory over New York Sen. Hillary Rodham Clinton by comparing it to Jesse Jackson’s victories in South Carolina during his runs for the presidency in the 1980s.

But in fact, the numbers don’t bear that out. If half as many black voters turned out, Obama still would have beaten Clinton, albeit not by as large a margin. Let’s say, for instance, that African American voters represented just 20 percent of the total electorate in South Carolina instead of the 55 percent they did — closer to, say, their share of the New York Democratic electorate. Assuming each candidate won the same proportionate support within each racial group, then Obama still would have won the primary with 34.6 percent of the overall vote to 32.6 percent for Clinton and 32.4 percent for former North Carolina senator John Edwards.

The reason is that Obama did pretty well among white voters as well. He received 24 percent of the white vote compared with 36 percent for Clinton, according to exit polls sponsored by The Washington Post and other news organizations. So even if the white vote were much larger, as in our scenario above, he would be close enough to Clinton that his overwhelming advantage among African Americans (he won 78 percent of the black vote to her 19 percent) would still be enough to put him over the top.