President George W Bush has appointed a new press secretary - conservative radio presenter Tony Snow.
Mr Snow replaces Scott McClellan, who resigned last week as part of a shake-up of Mr Bush's top staff.
Announcing the appointment, President Bush praised Mr Snow - who sometimes had disagreed with him.
Correspondents say Mr Snow, who was a speechwriter for the president's father, has sometimes criticised Mr Bush for not being conservative enough.
He currently hosts two shows on the Fox News network, which is owned by the media magnate Rupert Murdoch.
Mr Bush said Mr Snow understood the importance of the relationship between government and those who covered the government's work.
"My job is to make decisions and his job is to help explain those decisions to the press corps and the American people," Mr Bush said, as Mr Snow and Mr McClellan stood by his side.
Mr Snow told reporters: "One of the reasons I took the job is not only because I believe in the president, because believe it or not I want to work with you."
The 50-year-old is the first Washington pundit to take over the press lectern at the White House.
His record is already being closely examined to see whether he has expressed views that conflict with the president's.
Mr Snow, in an Associated Press interview on Tuesday, said: "It's public record. I've written some critical stuff. When you're a columnist, you're going to criticise and you're going to praise."
Correspondents say the White House will be hoping a former journalist may ensure a smoother ride with the press than it has enjoyed in recent months.
The BBC's James Coomarasamy, in Washington, says it is thought that Mr Tony Snow may have more of a policy-making role than his predecessor.
Mr Snow has called on the White House to fight back against its critics and he now gets the chance to practise what he's preached, our correspondent adds.