First, there is no relationship between how candidates perform among any particular group of voters in primaries and how they do with that segment in the general election. In 1992, Bill Clinton lost college-educated voters to Paul Tsongas in the early competitive primaries, but he went on to win that group in November by the largest margin any Democrat ever had. Similarly, John Kerry lost young voters in the competitive primaries in 2004 before going on to win them by a record margin in the general election.

Second, Democrats running for president have been losing white, non-college-educated voters since before Mr. Obama was elected to the Illinois legislature. Al Gore and Mr. Kerry each failed to win a majority of this bloc in the general election. With these voters, the size of the losing margin is what matters.

Mr. Gore lost them by 17 percentage points while winning the national popular vote. Mr. Kerry lost them by 23 points and the country by fewer than two and a half points. The last Democrat to win white, non-college voters was Bill Clinton, who carried them by a single point in the three-way races in 1992 and 1996.

By comparison, Mr. Obama is only two percentage points behind John McCain among these voters in the latest New York Times/CBS News poll. Another recent survey shows him down seven points.

In other words, Mr. Obama is faring better today with the white working class than did either Mr. Gore or Mr. Kerry.

Although Mr. Obama leads Mr. McCain in almost every national poll published this month, he cannot afford to take any constituency for granted. But he plainly has a path to victory. And the white working class does not seem poised to block his way.