Via Marc Ambinder, according to a new poll of residents of Arizona’s Maricopa County -- the state’s most populous and home to eight of its 10 largest cities --
“„McCain’s narrowing lead traces not to any sudden up-swelling in support for Obama, whose support has hovered around 38 percent for the past year and remains at that level today. Rather, it traces to a decline in support of McCain, especially among men, registered Independents and Latinos. Simultaneously, the proportion of voters who are uncommitted rose to 16 percent from only nine this May and Ralph Nader drew a small but important three percent, mostly from McCain.
“„The most obvious explanation for the tightening up of the race is that for the first time in any McCain race we can recollect, the usual 20 to 30 percent of Democrats who defect to McCain are now staying home. Today, only nine percent of Democrats are crossing over to McCain while 11 percent of Republicans are crossing over to Obama.