Senator instantly infamous remarks on how small-town Americans "cling" to their faith, their guns, and their xenophobia began drawing attention around 3:30 p.m. Friday.
Obama's aides went into radio silence, rebuffing requests to explain or respond while his rivals attacked him. At 6:30, his campaign put out a statement that, instead of explaining his words, threw the criticism back at his rivals. Then, just before 9:00 that evening, the candidate himself responded during a speech in Terre Haute, Indiana, with an attack of his own, expressing incredulity that his rivals had called him "out of touch."
"Out of touch? Out of touch? I mean, - it took him three tries to finally figure out that the home foreclosure crisis was a problem," he said, while also criticizing for her vote on to make declaring personal bankruptcy harder.
"She says I'm out of touch?"
The response was signature Obama: Attack first, sort out the details later, if at all. No apology, no immediate regret, just a sharp counterattack. For a candidate sometimes mocked for being too soft to win a political fistfight, he has shown an uncanny ability to take a punch, and then rear back and deliver one in return.
When Obama responds this way, it leaves him open to charges that he's undermining his so-called politics of hope. But, showing remarkable dexterity, he has a knack for using these flare-ups to pivot back to the central theme of his candidacy: that politics is broken, and he knows how to change it.
Obama, it turns out, has been a devout observer of a philosophy future President Bill Clinton laid out as far back as 1981.
"When someone is beating you over the head with a hammer, don't sit there and take it," then-Governor Clinton told Time Magazine. "Take out a meat cleaver and cut off their hand."
Many Democrats believe their two most recent nominees, Al Gore and John Kerry, ignored that rule, and they are loath to nominate another candidate susceptible to being portrayed as weak. So Obama and his inner political circle - strategist David Axelrod and campaign manager David Plouffe - have observed it religiously, dispelling an early perception that the candidate would wilt under fire from Clinton or Republicans.
Instead, when under attack, the candidate rarely acknowledges any fault - for such a move would offer critics an opening. In the case of his San Francisco remarks, perhaps the worst gaffe of his career, he conceded Saturday only that "if I worded things in a way that made people offended, I deeply regret that."
Obama's unexpected pugnacity also extends to include personal responses to tactical assaults, a level of sparring often left to spokespeople.
The examples are many, but the pattern first began to take shape last summer after a debate in South Carolina at which Obama said he would personally meet foreign dictators.
The remark appeared to be a slip, and in the spin room after the debate, Obama's chief strategist, David Axelrod, tried to explain it away.
But the next day, Clinton told the Quad City Times, an Iowa daily, that Obama had been "naïve and irresponsible" to offer meetings, an attack reported on the paper's website. That afternoon, Obama himself placed a call to the reporter who wrote the story.
It was Clinton, he said, who had been "irresponsible and naïve" to vote to authorize the war in Iraq. And he embraced his promise to meet the hostile leaders, casting Clinton's reluctance - a line his campaign continued to amplify throughout the fall - as similar to the Bush administration's stance.
Obama has eagerly pursued other attacks. He memorably mocked Clinton for finding evidence of untoward ambition in his elementary school writings. When Clinton called to "tur up the heat" on the Republicans, Obama suggested "more light" instead.
In late February, reporters traveling with Obama in Ohio learned - before the story hit the wires or the blogs - from Obama's staff that McCain had accused the Illinois senator of ignorance of the presence of Al Qaeda terrorists in Iraq.
Obama, taking the stage at Ohio State University minutes later, responded with vigor.
"John McCain thought that he could make a clever point," said Obama. "I have some news for John McCain. And that is that there was no such thing as al-Qaida in Iraq until George Bush and John McCain decided to invade Iraq."
More recently, when faced with the incendiary video of his former pastor Rev. Jeremiah Wright attacking Clinton, followed by more video of the minister's criticism of American, Obama eschewed the counterattacks. But nevertheless he hewed to a familiar course: no apology, no concession of wrongdoing. His position was that he hadn't been in the pews for Wright's reported controversial statements.
Obama's immediate responses, the campaign quickly decided, were insufficient. And so just six days later Obama sought to cast the issue in his own terms with a major speech on the easier aspect of Wright's words to address, race, while ignoring Wright's anti-American comments.
But the most recent flap over his remarks about small-town Pennsylvanians represented a return to form as he moved first to attack Clinton and McCain.
Then came what seemed to a departure. In a slow-motion roll-out that may have slightly prolonged the story, Obama tiptoed up to an apology, before returning to his comfort zone. On Sunday evening, with particular glee, he turned to Clinton's discussion of her childhood hunting.
"She's running around talking about how this is an insult to sportsmen, how she values the Second Amendment, she's talking like she's Annie Oakley!" he said at a stop in Pennsylvania. "Hillary Clinton's out there like she's on the duck blind every Sunday, she's packin' a six shooter! C'mon! She knows better. That's some politics being played by Hillary Clinton. I want to see that picture of her out there in the duck blinds."
By Avi Zenilman and Ben Smith