Once upon a time, abortion was a defining issue for many voters. In the late 1990s and early 2000s, partisan preferences on both sides were linked to strong religious and moral beliefs. Voters didn’t switch parties much.

In the last half a dozen years, voters have responded more to events, emerging issues, and leaders’ strengths and weaknesses. Many switched parties to vote for Obama. Some, many of them women, are switching now to vote for Romney.

Women tend to be more risk-averse than men, and the gender gap grew when Reagan Republicans were depicted as scaling back welfare-state protections.

The debates may have shifted the perception of risk. The downcast Obama and the cackling Biden may have sounded dangerously risky. Many women may have felt, as my e-mail friend’s wife said last winter, that they would feel safe if Romney were in charge.