He leads 53-41 among white women. From the summary of the new Washington Post/ABC poll:

McCain, lifted by increasing enthusiasm for his candidacy and a jump in support among white women, has wiped away Obama’s pre-convention advantages. Among all registered voters, the contest is now basically deadlocked — 47 percent for Obama, 46 percent for McCain. It is also about even among those who say they are most likely vote — 49 percent for McCain, 47 percent for Obama.