Time Magazine reported Thursday that Obama paid Biden a visit in June and delivered the warning - and did so again in December when he didn't see the Biden campaign operation improve.
He had been invited to the White House at Biden's invitation, after the two men served together as president and vice president for eight years.
'He expressed concern the re-election campaign was behind schedule in building out its field operations, and bottlenecked by Biden's insistence on relying upon an insular group of advisers clustered in the West Wing,' Time wrote, citing a Democratic insider.
While both White House and campaign officials act optimistic publicly, Time reported that behind closed doors they are scared.
