SPRINGFIELD, ILL. — Sleeves rolled up, Joseph R. Biden Jr. bounded onto an outdoor stage here Saturday and kicked off his campaign as Barack Obama's running mate with an emotional appeal to blue-collar voters and a blistering attack on John McCain.
Moments after Obama, the presumed Democratic presidential nominee, introduced Biden to a roaring crowd of supporters, the six-term senator from Delaware ripped into their opponent, tying McCain again and again to the unpopular President Bush.
"You can't change America when you supported George Bush's policies 95% of the time," Biden declared, his suit jacket cast aside in the sweltering heat.
Even as he expressed admiration for Republican McCain, a longtime friend and Senate colleague from Arizona, Biden said, "I say with every fiber of my being, I believe we cannot as a nation stand for four more years of this."
Party leaders heading to the Democratic National Convention, which starts Monday in Denver, enthusiastically embraced the new ticket and Biden's aggressive language after watching Obama's once-commanding lead slip away in recent national polls.
They dismissed Biden's criticisms of Obama and his miscues during the hard-fought Democratic primary season, when Biden made a short-lived run for the presidential nomination, as comments cast in the heat of a campaign.
McCain's camp quickly released a 30-second TV ad showing Biden praising McCain and saying that he didn't believe Obama was ready for the presidency. The Republican National Committee unveiled a new website criticizing Biden's long Senate record and recycling other comments he made about Obama.
Biden insisted Saturday that after watching Obama campaign, he is convinced he has the "judgment, intelligence and steel in his spine" to lead the nation.
Obama spoke first Saturday in a carefully choreographed event outside the Old State Capitol, the stately limestone edifice where Abraham Lincoln once worked and where Obama, a first-term senator from Illinois, launched his unlikely White House campaign 19 months ago.
"Joe won't just make a good vice president -- he will make a great one," Obama promised the cheering crowd, which police estimated at 35,000.
Many waved newly issued deep-blue Obama-Biden signs.
He praised Biden as a "working-class kid" from Scranton, Pa., who had become a world-class "statesman" -- a double-barreled appeal to working-class voters and those nervous about Obama's relative lack of foreign policy experience.
"He's an expert on foreign policy whose heart and values are firmly rooted in the middle class," Obama said. "He has stared down dictators and spoken out for American cops and firefighters."
Then, as the crowd roared approval, the 65-year-old Biden bolted from a side door of the Capitol and jogged onto the stage beside Obama. The two men shook hands, flung their arms around each other's shoulders and pumped their arms in the air.
Biden has a reputation as a long-winded orator. But he sounded much more impassioned Saturday than Obama, who was often low-key.
And Biden held little back in his attacks on McCain.
He mocked McCain's inability in an interview last week to recall how many houses he owns with his wife, Cindy, whose net worth is estimated up to $100 million.
While other families sit at the kitchen table and worry about paying bills, Biden said, McCain faces a choice: "He'll have to figure out which of the seven kitchen tables to sit at."
In one of the harshest criticisms the Democrats have leveled, Biden suggested McCain has lost his moral compass in his drive for the White House.
"I must tell you, frankly, I've been disappointed in my friend John McCain, who gave in to the right wing of his party and yielded to the very 'Swift Boat' politics that he once so deplored," he said.
Four years ago, some Republicans who supported Bush's reelection challenged combat medals awarded to Democratic nominee John F. Kerry, who had commanded a Swift Boat in Vietnam. Many of the charges were quickly proved false, but the Massachusetts senator's campaign never recovered. McCain, a former Navy aviator who was shot down and imprisoned in Vietnam, was among those who denounced the smears.
Praise from Clinton
Democrats, and even two Senate Republicans, praised Biden's foreign policy expertise, his national security credentials, and his appeal as an Irish Catholic to blue-collar voters -- all presumed gaps in Obama's resume. He is expected to work hard to win working-class Democrats who supported Hillary Rodham Clinton in the primary and who remain suspicious of Obama.
Clinton, who fought hardest and longest against Obama for the Democratic nomination, hailed his choice as running mate, though many of her supporters had hoped she would be chosen. The New York senator called Biden "an exceptionally strong, experienced leader and devoted public servant" who would make a "dynamic vice president."