A right-wing pundit who once urged President Bush to "stop cowering under the bed and start fighting back" was introduced today as the new White House press secretary.

Tony Snow, a Fox News commentator who used to work as a speechwriter for the first President Bush, replaces Scott McClellan as part of a drive to re-energise Mr Bush's team for his second term after a series of political disasters that have seen his poll ratings plummet.

Ahead of the appointment, American liberals have had a field day digging up some of Mr Snow's criticisms of the President, notably over his failure to rein in spending.

Introducing Mr Snow to the White House press corps, Mr Bush said: "For those of you who’ve read his columns and listened to his radio show, he sometimes has disagreed with me. I asked him about those comments, and he said, ‘You should have heard what I said about the other guy."’

Mr McClellan had served as Mr Bush's chief spokesman for three years and is one of a number of senior White House officials, including the former chief of staff Andrew Card, moving on amid popular disenchantment with the conflict in Iraq and anger at the mishandling of other crises, including Hurricane Katrina.

Mr Snow, 50, is a career journalist who took a sabbatical from the profession to become chief speechwriter to George H W Bush. He currently has his own politics show on Fox News Radio and a weekend television show on Fox News (both owned by News Corp, the ultimate parent of The Times).

Since news emerged that Mr Snow, who has recently fought a battle with colon cancer, was the White House's preferred candidate, many of his previous commentaries on Mr Bush's record as president have resurfaced.

According to remarks circulated by one liberal think-tank, the Centre for American Progress, Mr Snow wrote last year that Mr Bush's Republican supporters were becoming increasingly concerned that he was turning his back on the values that won his re-election.

"His wavering conservatism has become an active concern among Republicans, who wish he would stop cowering under the bed and start fighting back . . . ," Mr Snow wrote last November after Republicans failed to win the governor’s race in Virginia. "The newly passive George Bush has become something of an embarrassment."

Mr Snow has also called the president a leader who has "lost control of the federal budget", the architect of a "listless domestic policy" and a man who has "a habit of singing from the political correctness hymnal".

Before his appointment was confirmed, Mr Snow told the Associated Press: "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."

The appointment is considered an important one for the Bush Administration since Mr Snow will be the second most visible person in the White House after the President himself. As a smooth-talking Washington insider, it remains how he will fit in, however, with a White House full of Texans proud of their outsider status.

The fact that Mr Snow is a journalist and not like his predecessors over much of the past 30 years a PR professional, should also stand him in good stead, a point made by Howard Kurtz in an online column for the Washington Post.

Kurtz recalled that "in a less partisan time" it was considered a normal career move for ja journalist to become a White House spokesman, but recent presidents had opted for "political publicists who, by and large, have protected the boss, stuck to the talking points and felt comfortable stiffing the press".

"Some were helpful away from the microphones, of course, but they had spent their careers promoting, deflecting and denying rather than digging out facts," Kurtz said.

"All of which makes the Snow appointment a fascinating one, especially for an administration that has often seemed to give the media the back of its collective hand."

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