The White House has denied it threatened legendary Washington Post reporter Bob Woodward, as a media sideshow linked to a showdown over huge budget cuts consumed Washington.
A row which blew up over Woodward's criticism of Barack Obama's leadership on key economic questions became the latest cudgel in a deepening dispute over how the White House treats journalists.
Woodward, part of the team with Carl Bernstein that helped bring down ex-president Richard Nixon, took exception to a phone tirade and a follow-up e-mail sent by top Obama economic adviser Gene Sperling. In the e-mail, Sperling apologised for shouting at Woodward, but contested his belief that Obama was "moving the goalposts" by demanding Republicans agree to revenue increases as part of the latest attempt to cut the deficit.
"I think you will regret staking out that claim," said Sperling in an e-mail obtained by the Washington organisation Politico.
Woodward made clear in a follow-up interview with Politico that he saw Sperling's comments as a threat.
"I don't think it's the way to operate," Woodward said.
White House spokesman Jay Carney defended Sperling, a normally genial adviser, known for in-depth briefings on arcane economic policy.
"Gene Sperling, in keeping with a demeanour I have been familiar with for more than 20 years, was incredibly respectful," he said.
Carney said Sperling "referred to Mr Woodward as his friend and apologised for raising his voice. I think you cannot read those e-mails and come away with the impression that Gene was threatening anybody."
Carney, a former Time magazine White House correspondent who covered the Bush and Clinton administrations, said robust exchanges between reporters and officials were normal.