DENVER — For a month or more, Barack Obama's presidential campaign has seemed stuck in neutral, losing momentum -- and voters -- to the hard-punching Republican campaign of John McCain.
Obama was nothing but a "celebrity," McCain's spokesmen charged, an airy elitist out of touch with ordinary Americans. Polls showed Obama losing ground among blue-collar men, married women, even longtime Democrats.
"John McCain has had a 12 and 0 run," Sen. Richard J. Durbin (D-Ill.), one of Obama's political confidants, acknowledged.
So for Obama, this week's Democratic National Convention was more than a chance to win a transient bump in the polls; it was a desperately needed opportunity to relaunch his campaign and redefine his image.
The new Obama, unveiled before about 84,000 cheering supporters in a football stadium, is more combative than the old Obama -- and more sharply focused on the economic problems of the nation's working class.
The Barack Obama who launched his presidential campaign 18 months ago appealed for voters to rise above partisan division, embrace a politics of hope and, above all, end the war in Iraq.
The Obama who appeared Thursday as the Democrats' presidential nominee renewed all those appeals, of course.
But the centerpiece of his acceptance speech was a sharp-edged, almost populist, economic message, aimed directly at the middle-income voters who have been reluctant to sign up for his crusade.
"We measure the strength of our economy not by the number of billionaires we have or the profits of the Fortune 500, but by whether someone with a good idea can take a risk and start a business, or whether the waitress who lives on tips can take a day off and look after a sick kid," Obama said.
"Tonight, more Americans are out of work and more are working harder for less," he said. "The [government's] failure to respond is a direct result of a broken politics in Washington and the failed policies of George W. Bush."
And Republican nominee McCain, he added, has agreed with Bush "90% of the time."
"Sen. McCain likes to talk about judgment," Obama said, "but really, what does it say about your judgment when you think George Bush has been right more than 90% of the time?"
There, in a few sentences, was a distillation of Obama's new message: Ordinary people are hurting economically, the Bush administration has failed to respond, and a McCain presidency would represent nothing but "more of the same."
"Now, I don't believe that Sen. McCain doesn't care what's going on in the lives of Americans. I just think he doesn't know," Obama said, then mocked a recent McCain comment: "Why else would he define middle class as someone making under $5 million a year?"
"It's not because John McCain doesn't care. It's because John McCain doesn't get it," he said in his sharpest jab at his opponent.
Obama devoted 16 minutes of his 44-minute speech to the economy, only 4 minutes to the wars in Iraq and Afghanistan. As his aides had promised, he offered a newly concrete summary of what he proposes to do for the struggling middle class: a broad-based tax cut that would cover 95% of wage-earners, an elimination of the capital gains tax on small businesses, and an energy program focused on investment in renewable sources.
"This was not a classic Barack Obama speech," said Stephen Hess of the Brookings Institution, who has studied conventions since 1952. "It was not an elegant speech. But that may have been on purpose."
Republican pollster David Winston warned that Obama ran the risk of damaging his unifier image by launching bare-knuckled thrusts at his opponent.
"His attacks on McCain were pretty tough, and that's the one element of his speech where he was in danger of conflicting with his brand," Winston said.
"The question is: Will viewers interpret that as a harsh attack, or will they just view it as a contrast?"
Obama's chief strategist, David Axelrod, said the candidate did not believe he was moving away from his original call for a unifying, "post-partisan" brand of politics.
The speech, Axelrod said, was a key part of the Democrat's strategy for winning the election: Prevail in the debate over the economy, energize traditional Democrats and enlarge the electorate by turning out record numbers of African American, Latino and young voters.
"It's really very simple," Axelrod told reporters at a breakfast Thursday. "It's not going well for white working-class or any working-class people in this country. . . . People have actually lost ground during the last eight years, years that McCain suggests were years of great economic progress.
"Our thrust at the convention was to put a focus on the economy because that is a central concern of most voters," he said. "People are struggling in this country, and that is a defining issue."
Axelrod and campaign manager David Plouffe said that despite nationwide polls showing a tight race, they are confident that Obama can pile up a majority of electoral votes.