Alabama and Georgia gave Obama three straight Southern triumphs. Like last month's win in South Carolina, they were powered by black votes.
Democrats and Republicans alike said the economy was their most important issue. Democrats said the war in Iraq ranked second and health care third. Republican primary voters said immigration was second most important after the economy, followed by the war in Iraq.
The survey was conducted in 16 states by Edison Media Research and Mitofsky International for The Associated Press and television networks.
Already, the campaigns were looking ahead to Feb. 9 contests in Louisiana, Nebraska and Washington state and Feb. 12 primaries in Maryland, Virginia and the District of Columbia. And increasingly, it looked like the Democrats' historic race between a woman and a black man would go into early spring, possibly longer.
The de facto national primary was the culmination of a relentless campaign that moved into overdrive during Christmas week.
After a brief rest for the holiday, the candidates flew back to Iowa on Dec. 26 for a final stretch of campaigning before the state's caucuses offered the first test of the election year. New Hampshire's traditional first-in-the-nation primary followed a few days later, then a seemingly endless series of campaign days interspersed by debates and a handful of primaries and caucuses.
Along the way, the poorest performers dropped out: Democratic Sens. Joe Biden and Chris Dodd, New Mexico Gov. Bill Richardson and Rep. Dennis Kucinich of Ohio; and Republican Reps. Duncan Hunter and Tom Tancredo, and former Tennessee Sen. Fred Thompson.
Former Sen. John Edwards pulled out of the Democratic race last week, and former New York Mayor Rudy Giuliani left the Republican field.
Edwards offered no endorsement as he exited, instead leaving Obama and Clinton to vie for help from his fundraisers and supporters.