WASHINGTON (AP) -- Barack Obama packed in a Nebraska crowd of over 10,000, Chelsea Clinton spoke up for her mom and Mike Huckabee laid out a full plate of Kansas events like he never heard the Republican race is supposed to be over. So goes the effort to win four Democratic and three Republican presidential nomination contests on the weekend -- a round getting less than the full treatment by the remaining hopefuls, but plenty of attention still.... There was plenty of drama for the two Democrats, competing for 161 delegates Saturday in Washington state, Louisiana, Nebraska and the Virgin Islands, followed by Maine caucuses with 24 delegates Sunday. In strongly Republican and sparsely populated Nebraska, Obama spoke to the huge crowd at an Omaha arena Thursday, exhorting: ''You're here because you don't want to just be against something. You want to be for something. Chris Slaughter, 20, heard the speech and said: ''He's a once-in-a-generation candidate.'' Chelsea Clinton campaigned for her mother, taking questions for an hour from students in Lincoln. Many asked about Hillary Clinton's efforts to establish universal health care -- her failure in the 1990s and her renewed plans now. ''It's not how people react when they succeed but how they react when they fail,'' said Chelsea. ''She learned from that experience.'' Usually a quiet presence with her mother on the trail, she planned to meet students in Omaha on Friday. Obama was the only candidate campaigning in all four states; Clinton planned stops in Washington and Maine, leaving Louisiana and Nebraska to husband Bill and daughter Chelsea.... *** A look at the races: WASHINGTON CAUCUSES: The stakes: 78 Democratic delegates, 18 GOP delegates. ...Obama is thought to have an advantage in the caucuses, which are dominated by party activists, especially in liberal Seattle. However, Washington has a strong history of electing women..... LOUISIANA PRIMARIES: The stakes: 56 Democratic delegates, 20 Republican delegates. ...A heavy ...