By JEFF ZELENY
Senator Barack Obama claimed the Democratic presidential nomination on Tuesday night, prevailing through an epic battle with Senator Hillary Rodham Clinton in a primary campaign that inspired millions of voters from every corner of America to demand change in Washington.
A last-minute rush of Democratic superdelegates, as well as split results from the final primaries in Montana and South Dakota, pushed Mr. Obama over the threshold of 2,118 delegates needed to be nominated at the party’s convention in Denver in August. The victory for Mr. Obama, the son of a black Kenyan father and white Kansan mother, broke racial barriers and represented a remarkable rise for a man who just four years ago served in the Illinois State Senate.
“You chose to listen not to your doubts or your fears, but to your greatest hopes and highest aspirations,” Mr. Obama told supporters at a rally in St. Paul. “Tonight, we mark the end of one historic journey with the beginning of another — a journey that will bring a new and better day to America. Because of you, tonight, I can stand before you and say that I will be the Democratic nominee for president of the United States.”
Mrs. Clinton paid tribute to Mr. Obama, but she did not leave the race. “This has been a long campaign and I will be making no decisions tonight,” Mrs. Clinton told supporters in New York. She said she would be speaking with party officials about her next move.
In a combative speech, she again presented her case that she was the stronger candidate and argued that she had won the popular vote, a notion disputed by the Obama campaign.
“I want the 18 million Americans who voted for me to be respected,” she said in New York to loud cheers.
But she paid homage to Mr. Obama’s accomplishments, saying, “It has been an honor to contest the primaries with him, just as it has been an honor to call him my friend.”
Mr. Obama’s victory moved the presidential campaign to a new phase as he tangled with Senator John McCain of Arizona in televised addresses Tuesday night over Mr. Obama’s assertion that Mr. McCain would continue President Bush’s policies. Mr. McCain vigorously rebuffed that criticism in a speech in Kenner, La., in which he distanced himself from the outgoing president while contrasting his own breadth of experience with Mr. Obama’s record.
“The American people didn’t get to know me yesterday, as they are just getting to know Senator Obama,” Mr. McCain told supporters. Mr. Obama’s victory capped a marathon nominating contest that broke records on several fronts: the number of voters who participated, the amount of money raised and spent, and the sheer length of a grueling battle. The campaign, infused by tensions over race and sex, provided unexpected twists to the bitter end as Mr. Obama ultimately prevailed over Mrs. Clinton, who just a year ago appeared headed toward becoming the first woman to be nominated by a major party. The last two contests reflected the party’s continuing divisions, as Mrs. Clinton won the South Dakota primary and Mr. Obama won Montana.
The race drew to its final hours with a burst of announcements — delegate-by-delegate — of Democrats stepping forward to declare their support for Mr. Obama. The Democratic establishment, from former President Jimmy Carter to rank-and-file local officials who make up the ranks of the party’s superdelegates, rallied behind Mr. Obama as the day wore on.
When the day began, Mr. Obama needed 41 delegates to effectively claim the nomination. Just as the polls began to close in Montana and South Dakota, Mr. Obama secured the delegates he needed to end his duel with Mrs. Clinton, which wound through every state and territory in an unprecedented 57 contests over five months.
Every time a new endorsement was announced at the Obama headquarters in Chicago, campaign workers interrupted with a booming round of applause. They are members of Mr. Obama’s team — a political start up — that is responsible for defeating one of the most tried and tested operations in Democratic politics.
While the Democratic race may have ended, a new chapter began in the complicated tensions that have defined the relationship with Mr. Obama and Mrs. Clinton.
On a conference call with members of the New York Congressional delegation on Tuesday, Mrs. Clinton was asked whether she would be open to joining a ticket with Mr. Obama. She replied that she would do whatever she could — including a vice presidential bid — to help Democrats win the White House.
In his speech on Tuesday evening, Mr. Obama paid respect to his rival.
“Our party and our country are better off because of her,” Mr. Obama said, “and I am a better candidate for having had the honor to compete with Hillary Rodham Clinton.”
Before she arrived at her rally on Tuesday in New York City, Mrs. Clinton and a few close advisers huddled at her home in Chappaqua, N.Y., to discuss the timing of her departure from the race. In the afternoon conference call she conducted with fellow New York lawmakers, she asked their patience as she decides upon her next move.
Representative Nydia M. Velásquez, Democrat of New York, asked Mrs. Clinton whether she would consider teaming up with Mr. Obama. “She said that if it’s offered, she would take it,” Ms. Velásquez said.
Mrs. Clinton said she would do “anything to make sure a Democrat would win,” according to several participants on the call. While her advisers played down the remark’s significance, the Democrats on the call said that by not demurring or saying she would simply think about it, they said they were left with the impression that it was an offer that she wanted to at least consider.
“If Senator Obama asked her to be the V.P., she certainly would accept that,” said Representative Carolyn McCarthy, Democrat of New York. “She has obviously given some thought to this.”
Neither Mr. Obama nor his associates commented on the speculation, and he made no reference to it in his speech on Tuesday evening in Minnesota, which was delivered at the same arena in which Mr. McCain is expected to accept the Republican nomination at the party’s convention in September.
“You can rest assured that when we finally win the battle for universal health care in this country, she will be central to that victory,” Mr. Obama said. “When we transform our energy policy and lift our children out of poverty, it will be because she worked to help make it happen.”
The competition between Mr. McCain and Mr. Obama has been sharpening for weeks, but the close of the Democratic primary formally raised the curtain to a five-month general election contest. The race, as their respective speeches foreshadowed on Tuesday evening, will unfold against a backdrop of an electorate that is restless about soaring gas prices, mortgage foreclosures and the Iraq war.
It is also a generational battle of personalities and contrasting styles. Mr. McCain staged an evening event in Louisiana, so he would be included in the evening’s television narrative that otherwise belonged to Democrats.
About two hours later, Mr. Obama responded in a speech before a thousands of supporters.
“There are many words to describe John McCain’s attempt to pass off his embrace of George Bush’s policies as bipartisan and new,” Mr. Obama said. “But change is not one of them.”
Michael M. Grynbaum contributed reporting.