It was a prescient warning.
Mr. Obama, who arrived here five days ago after a commanding triumph in the Iowa caucuses, had planned to leave New Hampshire on a similar high. But a defeat by Senator Hillary Rodham Clinton here on Tuesday evening startled Mr. Obama and ensured that the fight for the Democratic presidential nomination remained fully engaged.
“We know the battle ahead will be long, but always remember that no matter what obstacles stand in our way, nothing can stand in the way of the power of millions of voices calling for change,” Mr. Obama said, speaking at a rally of crestfallen supporters. “We have been told we cannot do this by a chorus of cynics that will only grow louder and more dissonant in the days and weeks to come.”
For the last five days here, Mr. Obama made one appeal above all to the legions of voters who turned out at rallies from dawn to dusk to see him: Prove that Iowa was not a fluke. He made that pitch again and again to audiences, which spilled from gymnasiums into side rooms and from opera houses onto snow-covered sidewalks, a tableau of young and old pressed closely together as they cheered his historic candidacy.
In the end, though, it was another historic candidacy — that of Senator Hillary Rodham Clinton — that appealed to more voters in New Hampshire, particularly women who broke with Mr. Obama in significant numbers in the closing hours of an accelerated campaign here.
Mr. Obama was counting on a New Hampshire victory to serve as a permission slip for Democratic leaders across the country to step forward to support his candidacy. He was hoping to trade the title of insurgent candidate for the perilous crown of front-runner. But the race is now a draw between the two rivals — with John Edwards of North Carolina, who came in a distant third, vowing to continue — and a furious scramble lies ahead.
With a confidence buoyed by a series of polls that consistently showed Mr. Obama leading Mrs. Clinton by as many as 10 percentage points, the Obama campaign was shaken by the loss as the final ballots were tabulated from a primary election held on a glorious springlike day where a record number of Democrats turned out.
If Mr. Obama had hoped to leave New Hampshire as a soaring victor, on his way to seizing the air of inevitability that had belonged for months to Mrs. Clinton, his narrow loss underscored the challenges that lie ahead for turning a political movement into an electoral success. As he addressed his supporters in a gymnasium at Nashua High School on Tuesday evening, he showed no signs of relinquishing his fight.
“When we’ve been told we’re not ready or we shouldn’t try or we can’t, generations of Americans have responded with a simple creed that sums up the spirit of a people,” Mr. Obama said. “Yes, we can. Yes, we can.” Throughout the evening, the confidence of Mr. Obama’s campaign gradually fell as returns poured in from across the state, which never put him over Mrs. Clinton. Aides said they believe that women rallied behind Mrs. Clinton in the final hours of the race, when news coverage was dominated by accounts of her nearly breaking into tears as she answered a voter’s question.
With Mr. Obama winning in Iowa and Mrs. Clinton winning in New Hampshire, a fresh dose of uncertainty was injected into the race as it moves to Nevada and South Carolina before contests in 22 states take place on Feb. 5. Mr. Obama was still hoping to win a crucial union endorsement in Nevada, where he dispatched his top aides from Iowa to organize the state.
Since Mr. Obama’s victory in Iowa, the volume of calls and inquiries into his campaign had more than doubled, with financial contributors, policy supporters and volunteers eager to join the campaign. He is flying on Wednesday to New York, in the heart of Mrs. Clinton’s territory, to hold a fund-raiser and to stage a campaign rally in New Jersey. Both states are among those with contests on Feb. 5.
“I am still fired up and ready to go,” Mr. Obama said. “First of all, I want to congratulate Senator Clinton on a hard-fought victory here in New Hampshire. She did an outstanding job.”
Those words seemed to be the only kind ones spoken between the two on Tuesday evening. In the final days of the race, Mrs. Clinton and former President Bill Clinton raised sharp questions about the viability of Mr. Obama’s candidacy, and Democrats were bracing for a combative race to come, with two well-financed campaigns and a series of primaries and caucuses ahead.
A victory for Mr. Obama, which even most of Mrs. Clinton’s advisers were predicting, would have opened the door for many Democratic leaders to coalesce around his candidacy.
As supporters filed out of the rally on Tuesday evening, Mr. Obama’s advisers declined to discuss the election results. They said they were moving on to the races ahead.
But Mr. Obama’s words from a rally on Monday, perhaps, provided the best explanation.
“It is very important for us all to be clear,” Mr. Obama said, “that we have not won anything yet.”