Not unlike Huckabee's support from evangelicals, Obama's strength among young voters and independents represents challenge as well as opportunity for him; as a general rule, young adults don't turn out as reliably as their elders, and turnout by independents in Democratic primaries is not always high (indeed, depending on the state, not always allowed). An exception, though, is New Hampshire, where independents participate in very large numbers. It votes Tuesday.
Perhaps most remarkable in the Democratic contest was the result among women, the group to which Clinton has owed her lead in national polls. In Iowa, Obama beat Clinton by 35 percent to 30 percent among women. He did better still among men, with 35 percent support, to 24 percent for Edwards and 23 percent for Clinton.
Obama also won whites, by a six-point margin, 33-27 percent over Clinton; they accounted for 93 percent of Democratic caucus-goers. In another challenge to Clinton, while she has polled competitively among blacks nationally, Obama won blacks in Iowa with 72 percent support, his single best group. And there are more African-American voters in many other states (New Hampshire is an exception) than in Iowa.
In the Republican race, other ways to view the outcome all come back to the prism of religion. Thirty-six percent said it mattered "a great deal" that a candidate share their religious belief, and Huckabee won 56 percent of them, with Romney and McCain far behind at 11 percent each. No wonder: Eighty-five percent in this group were evangelicals.
By contrast, among those who said sharing religious belief was not important -- about a third of Republican caucus-goers -- Romney won 39 percent, Huckabee just 11 percent.
Huckabee beat Romney by wide margins among voters who cared most about a candidate who "shares my values" (44-26 percent) or who "says what he believes" (33-14 percent, a particular weakness for Romney) -- but in both cases, only among evangelicals who said so.
For his part, Romney -- who campaigned the longest and spent the most in Iowa -- beat Huckabee by even wider margins among those who cared most about the candidate who has the right experience (37-9 percent) or who has the best chance to win in November (51-8 percent). But these were much smaller groups.
There also was a generation gap in the Republican contest; among participants under age 45, Huckabee had 39 percent support, Romney just 22 percent. Seniors, meanwhile, divided about evenly between the two.
Another notable result in the Republican race was that turnout among conservatives was well up - they accounted for 88 percent of GOP caucus-goers, up from 73 percent in 2000. That included 45 percent "very conservative," up from 34 percent in 2000. Again, it's about evangelicals, who were substantially more likely to identify themselves as conservatives. If bitter for Romney, the result also wasn't ideal for John McCain, who'd reached in the closing days for clear third place in Iowa but didn't get there, running neck and neck with Fred Thompson. McCain did best with Republican caucus-goers who favored experience and whose top issues were the war in Iraq and terrorism, and he found strong support among moderates and independents. But these were relatively small groups.