You are entirely correct when you say,
...while women as a whole vote Democratic, white women don't. George W. Bush smoked John Kerry with them in 2004 after edging Al Gore in that group in 2000. He beat the Massachusetts senator by 11 points--or roughly what McCain is beating Obama by at the moment, according to the Post. Bill Clinton won 48 percent of white women in 1996, to Bob Dole's 43 percent, with Ross Perot claiming 8 percent, and he tied George H. W. Bush among the demographic in 1992, with 41 percent each (Perot took 18 percent).
But Clinton's appeal was unique: The elder Bush took 56 percent of white women in 1988, and Ronald Reagan took 62 percent in his 1984 landslide. Reagan won 52 percent to Jimmy Carter's 39 percent (John Anderson pulled 8 percent) in 1980. Gerald Ford won the group in 1976, with 52 percent to Carter's 36.
That said, however, let me hone one small unnoticed point: White women as a group haven't supported the Democratic candidate in a presidential election in a while, but it is actually white, married women who vote most Republican of any female demographic--much more so than single or widowed white women or women of color, married or unmarried.
Look at these data from the 2004 presidential election compiled by USA Today based on various Gallup polls:
--Democratic advantage: +5% points
--Democratic advantage: -13
--Democratic advantage: +25
--Democratic advantage: +38
This makes much more sense when one considers these groups' income levels.
Married white women are the richest demographic of any group of women. As a result, they tend to be less dependent on government subsidy programs (which Democrats support) and more concerned about reducing taxes (an issue on which Republicans claim supremacy).
By Bonnie Erbe