In 1992, Jerry Brown kept repeating his campaign's 800 number so people could phone in contributions. In 2008, and especially this time, candidates are raising money through email. That's far faster and cheaper than snail mail.
Money can rush in rapidly. Scott Brown's Massachusetts Senate campaign was taking in $1 million in the last days after polls showed him within striking range. Herman Cain was deluged with millions after the news media reported he had been accused of sexual harassment.
But current Iowa polling But current Iowa polling shows Newt Gingrich, Herman Cain and Mitt Romney in a tie for the lead there. According to the tracker, in the 38 days since Oct. 15, Gingrich has had Iowa campaign events on eight days, Cain on three and Romney on two. Rick Santorum has had Iowa events on 19 of those days and is the only candidate to have held them in all the state's 99 counties. But he's averaging only 4 percent in Iowa polls taken during that time.
Instead of personal contact, voters seem to be making decisions based on performance in debates, which thanks to cable news have been viewed by many more voters than in the past, and by what they've been reading and watching on the Internet. [See here for a survey on how debates are influencing Republicans.]
Third, religious and social conservatives drive GOP nominations.
Iowa caucuses are open to anyone who shows up, and in 2008 only 119,000 Republicans did so in a state of 3 million. That leaves a large potential reservoir of newcomers this time.
Iowa pollster Ann Selzer reports less enthusiasm among evangelical Christians in this cycle, and some local Republicans predict a larger turnout this time. That could mean an infusion of new participants, with results that can't be extrapolated from past contests. [Also note that libertarian Ron Paul is doing well in some Iowa polls.]