It was from NBC, which said that Obama had overpromised when he said Americans who liked their insurance could keep it, and that the president knew that many people would see their coverage change. (Agencies)
White House officials quickly began firing off a barrage of tweets on Twitter, which has become one of the administration's most potent and relied-upon weapons in trying to shape public opinion and media reports.
Josh Earnest, the principal deputy press secretary to Obama, began the assault with a series of tweets that said the healthcare law did protect Americans against changes in their coverage - unless insurers altered such coverage.
"NBC 'scoop' cites normal turnover in the indiv insurance market," Earnest tweeted to his 9,500 followers on Twitter.
The message was retweeted 166 times, potentially reaching another 164,000 people, according to Twitonomy, a Twitter analytics tool.
During the next hour, White House staffers would tweet and retweet messages about the story more than a dozen times, including tweets directly to the NBC reporter.
The debate continues over whether Obama has been misleading about the healthcare law. But it's clear that in many ways, Twitter has become as important in the West Wing's communications arsenal as daily press briefings. Twitter's 140-character messages are faster than a press release, with broader and more direct reach than appearances on cable television.
Under a strategy championed by Obama's senior adviser Dan Pfeiffer, the White House has doubled its footprint on Twitter since July, giving official accounts on the social media web site to more than a dozen additional communications staffers.
The White House's Twitter army is the lead player in an intense war of messaging on social media in Washington, a conflict that also involves a range of lawmakers, bureaucrats, conservatives and liberals.
Virtually every day, the White House is the focus of Twitter barbs from conservative groups such as the Heritage Foundation, online personalities such as Erick Erickson of RedState.com and Republican staffers such as Brendan Buck, a spokesman for House Speaker John Boehner.
But the White House operation stands alone in its aggressiveness, analysts say.
"You never find an organization that is collectively this good at Twitter," said Peter LaMotte, head of digital communications practice at Levick, who advises major corporations on using social media.
SPINNING AND 'SHAMING'
Obama's White House was an early adopter in Washington's Twitter wars. Obama's campaign team helped get him elected and re-elected with its deft use of social media.
Before its initial public offering on November 7, Twitter <TWTR.N> sought to show the web site's potency by recalling in its regulatory filing how Obama's campaign team had used Twitter to declare victory, tweeting "Four more years" in a message viewed about 25 million times.
Since 2009, Obama's administration has sent tweets through a raft of well-followed but faceless accounts such as @whitehouse and @blog44, gradually adding individuals who work there.
The administration's most prominent Twitter account, @BarackObama, has more than 39 million followers and is actually run by Organizing for Action, a pro-Obama group with close ties to the White House, rather than by Obama and his staff.
Others are more directly engaged on Twitter. Press Secretary Jay Carney has tweeted as @PressSec since 2010 and has 455,360 followers. White House photographer Pete Souza has 92,000.
After staffers were trained by the White House counsel's office on what they could - and should not - say on social media, they recently began posting personality-driven tweets.
"Hey @PressSec, finally got on twitter. #whatcouldpossiblygowrong?" Deputy Press Secretary Eric Schultz tweeted to Carney in his maiden tweet on August 1.
Schultz said the West Wing views Twitter as a way to "engage in real time (communication) so that as many folks as possible understand our perspective."
That was the case during the 16-day government shutdown last month, as the administration used Twitter to boost its calls for Boehner to call a House vote to end the shutdown.
At one point, Boehner appeared on ABC's "This Week with George Stephanopoulos," a popular Sunday morning political show.
During and after the interview, the White House Twitter brigade fired off a flurry of tweets that amounted to the administration's only comment that day on Boehner's interview.
"If there are not votes to open the government as Speaker Boehner says, why is (he) so afraid to call the vote and prove it?" Pfeiffer tweeted in one message to his 55,000 followers that was retweeted 126 times to more than 71,000 others.
A similar tweet from Carney was retweeted 448 times to 203,000 people.
During the shutdown, West Wing staffers frequently "corrected" storylines from reporters or Republican aides using Twitter.
"It's essentially public shaming," said Levick's LaMotte, wondering whether the White House's Twitter strategy has dialed up the tension in the administration's already adversarial relationship with some conservatives.
Indeed, it often seems that conflicts on Twitter aren't exactly elevating the public discourse on politics.
Last month, West Wing staffers waded into Twitter fights with Republicans, even as Carney was giving a press briefing.
Deputy Press Secretary Schultz traded darts with Rory Cooper, an aide to Republican House Leader Eric Cantor, about whether Obama had done enough outreach to Congress.
"Five years, and you have to point out five social events," Cooper tweeted.
It was from NBC, which said that Obama had overpromised when he said Americans who liked their insurance could keep it, and that the president knew that many people would see their coverage change.