Minority women vote overwhelming for the Dems as the graphs I provided show. In 2012 Black women made up 8% of the total electorate, Latinas 6%, and all others 5%. White women made up 38% of the total electorate. So combining the percentages white women 38% versus minority women 19% a two to one difference. When you weight these constituencies by how they voted, the minority women skew the data far more to the Dems.
Since maybe 65 to 70% of those single women are white, white single women almost certainly were a majority Dem vote. Perhaps less than 2008 thru 2012, but still....
I don't think you can make that assumption re percentage of those being single. Here are some BLS data that show that the percentage of white women who ever married is 90.4% compared to blacks 68.3%.
It would be interesting to learn what percentage of single women are white, but I doubt it is 60% or 70%. Non-Hispanic whites only make up 69% of the population (2012 figures).
The fact that it is difficult to find out this information about the voting rates by single women by race should set off alarm bells. I have no doubt that the data would show that the proposition that Reps are losing the single women vote is more of a function of race than marital status. In 2012 single women were 23% of the electorate and voted 67% to 31% for Obama and married women, 31% of the electorate voted 53% to 46% for Romney. Since white women marry at a much higher rate than blacks, it is easy to understand why married women tend to vote Rep.
2 or more races? I thought that number is much higher