Senator Barack Obama defeated Senator Hillary Rodham Clinton in the Maine caucuses on Sunday, giving him his fourth victory this weekend as he headed into three more state contests on Tuesday.
With 90 percent of Maine’s precincts reporting, Mr. Obama received 58.7 percent of the vote, compared with 40.7 percent for Mrs. Clinton.
Voter turnout in parts of Maine was reported to be strong on Sunday afternoon, despite a snowstorm. The Portland Press Herald reported on its Web site that there were long lines at the caucus in Portland, while a large crowd in Cape Elizabeth delayed the start of the caucus there by more than an hour.
Mr. Obama’s victory in Maine follows those in Washington, Louisiana and Nebraska on Saturday. Combined with his advantage in fund-raising, these victories should give him momentum going the primaries on Tuesday in Virginia, Maryland, and Washington, D.C.
Mrs. Clinton’s defeat in Maine came on the same day as her campaign manager stepped down. A Clinton spokesman said the departure of Patti Solis Doyle as campaign manager was not a shakeup, and Ms. Solis Doyle said in an e-mail statement that she would serve as a senior adviser to the campaign. She will be replaced by Maggie Williams, another senior adviser to the campaign.
In the Republican contests on Saturday, Mike Huckabee won the caucuses in Kansas and, by the barest of margins, the Louisiana primary, in a setback for Senator John McCain as he tries to rally the party around him as its nominee. But in Washington, the state party declared Mr. McCain the winner of its caucuses on Saturday night, after a close race with Mr. Huckabee.
Mr. McCain’s opponents have tried to cast doubt on his appeal to conservative voters throughout the campaign. But on “Fox News Sunday,” President Bush said emphatically that Mr. McCain was a conservative, although the president noted that the Arizona senator “has got some convincing to do to convince people that he is a solid conservative, and I’ll be glad to help him if he is the nominee.”
“I know his convictions,” President Bush said. “I know the principles that drive him and no doubt in my mind that he is a true conservative.”
While Mr. Obama had been expected to win the contests on Saturday, the margin of his victories were surprising, particularly in Nebraska and Washington, which offered the day’s biggest trove of delegates. In both states, he captured 68 percent of the vote in caucuses, compared with Mrs. Clinton’s roughly 32 percent. In Louisiana, Mr. Obama won 57 percent, to Mrs. Clinton’s 36 percent.
“We won in Louisiana, we won in Nebraska, we won in Washington state,” Mr. Obama said Saturday at the Virginia Democrats’ Jefferson-Jackson Dinner in Richmond, Va. “We won North, we won South, we won in between. And I believe that we can win in Virginia on Tuesday if you’re ready to stand for change.”
Mr. Obama and Mrs. Clinton both campaigned in Virginia on Sunday.
While Mr. Obama’s victories are significant, the Democratic Party awards delegates proportionally, so Mrs. Clinton stands to walk away from the contests with a considerable number. The Associated Press estimated that Mr. Obama won 69 delegates in the three states on Saturday, while Mrs. Clinton won 40 delegates. The A.P. also estimated that Mr. Obama won at least 13 more delegates in the Maine caucuses, while Mrs. Clinton won at least eight more delegates.
Both campaigns have dug in for a long and fierce delegate fight.
Mrs. Clinton’s advisers had predicted she might not win any of the contests in February, and said she was looking ahead to March 4, when voters in Rhode Island and particularly Ohio and Texas will decide the next big bloc of delegates.
With the fight for the nomination extending beyond the 22 contests last Tuesday, voters in a fresh batch of states have suddenly found themselves in the thick of the most competitive primary in a generation. In past years they tended to cast their votes well after the nominee was effectively chosen.
On Saturday, with the contest so close, excitement ran high, as did turnout.
In Nebraska, The Omaha World-Herald reported that organizers at two caucus sites had been so overrun by crowds that they abandoned traditional caucusing and asked voters to drop makeshift scrap-paper ballots into a box instead. In Sarpy County, in suburban Omaha, traffic backed up on Highway 370 when thousands of voters showed up at a precinct where organizers had planned for hundreds.
In Washington, the Democratic party reported record-breaking numbers of caucusgoers, with early totals suggesting turnout would be nearly be nearly double what it was in 2004 — itself a record year — when 100,000 Democrats caucused.
Mrs. Clinton said nothing about the day’s results as she spoke to a cheering crowd at the Jefferson-Jackson day dinner shortly after Mr. Obama was named the winner of the Nebraska and Washington caucuses.
Her campaign argued that Mr. Obama had greatly outspent her on television advertisements in all three states.
“Although the next several states that hold nominating contests this month are more favorable to the Obama campaign, we will continue to compete in them and hope to secure as many delegates as we can before the race turns to Ohio, Texas and Pennsylvania,” said a spokesman, Phil Singer.
The results on the Republican side provided some surprise, particularly since Mr. Huckabee’s showings in Kansas and Louisiana came as Mr. McCain seemed headed to the nomination.
Mr. Huckabee declared that the voters had been heard from. “They spoke with one voice,” he said. “They said I am the authentic conservative in this race.”
The McCain campaign played down Mr. Huckabee’s victories, saying they had been expected.
“John McCain is the presumptive nominee in this race and our path forward is unchanged by today’s results,” a spokeswoman, Jill Hazelbaker, said. “Our focus remains the same: uniting the Republican Party to defeat Democrats in 2008.”
Even before any results were in Saturday, despite the daunting number of delegates Mr. McCain has amassed, Mr. Huckabee told reporters he was not pulling out of the race. Mr. Huckabee, a pastor before he became governor of Arkansas, said: “I didn’t major in math. I majored in miracles, and I still believe in them, too.”
Later, after the results from Kansas were in, he said Republican leaders “ought to be begging me” to stay in.
“It’s an awfully weak party that can’t handle competition,” he said. “Competition breeds excellence.”
Mr. Huckabee compared himself to Ronald Reagan when he challenged President Gerald R. Ford for the 1976 nomination. “He was the pariah of the party,” he said. “Now people love Ronald Reagan.”
In the Republican caucuses in Kansas, Mr. Huckabee won 60 percent of the vote, Mr. McCain 24 percent and Representative Ron Paul of Texas 11 percent. The AP reported that Mr. Huckabee picked up all 36 Kansas delegates.
The Democrats held their caucuses in Kansas last Tuesday, with Mr. Obama the winner.
Mr. Huckabee also won the Louisiana primary, gaining 43 percent of the vote, compared with Mr. McCain’s 42 percent. But Mr. McCain came in first in the Washington caucuses, with 26 percent of the vote, compared with 24 percent for Mr. Huckabee and 21 percent for Representative Ron Paul of Texas.
Mr. McCain is far enough ahead in the delegate race that his advisers have said it would be all but impossible for anyone else to win the nomination. His other chief competitor, Mitt Romney, bowed to those odds when he suspended his campaign on Thursday.
Early in the day, after addressing the Conservative Political Action Conference in Washington, Mr. Huckabee said he had no intention of dropping out until one of the Republican candidates had amassed the 1,191 delegates needed to be the nominee. Before Saturday’s voting, Mr. McCain had 703 delegates, Mr. Huckabee, 190, and Mr. Paul, 42.
Asked if he saw any cost to staying in the race, Mr. Huckabee thought for a moment before saying no. "I have nothing else to do,” he said with a smile.
Reporting was contributed by Paul Vitello from Washington, Katharine Q. Seelye from Bangor, Maine, Jeff Zeleny from Chicago, and Jack Lynch from New York.