President Barack Obama on Friday called the family of a campaign staffer who collapsed in the Chicago headquarters and later died, Obama's campaign said.
The staffer, 29-year-old Alex Okrent, worked in the campaign's advertising department, the Chicago Sun-Times said in a report, which campaign officials acknowledged was accurate.
The president offered his condolences to Okrent's family and spoke with other members of his campaign staff in a conference call, his campaign said.
Obama was campaigning in Virginia on Friday.
Okrent had worked on Obama's 2008 presidential campaign and his 2004 U.S. Senate campaign, the Sun-Times report said.
Presumptive Republican presidential nominee Mitt Romney and his wife, Ann Romney, acknowledged Okrent in a tweet after the news emerged.
"Ann & I were deeply saddened to learn of the death of Alex Okrent," he tweeted. "Prayers are with Alex's loved ones and the entire Obama campaign team."
David Axlerod, a senior adviser to Obama's campaign, tweeted in reply to Romney: "Thank you, governor. Alex was a beloved member of our team. It's been a very emotional day."
No further details were immediately available.