Bush's Democratic challenger in the November 2 election, John Kerry, has raised questions over US national security, what had been Bush's strong suit.

The president adhered to the Iraq war as a cornerstone of his "war on terror."

"Because we acted, the world is more free and America is more secure," Bush has said repeatedly.

The former chief of counter-terrorism at the White House, Richard Clarke, stoked the debate this week in a book and in public testimony before a September 11 commission of inquiry with strong criticism of Bush's handling of the matter.

Clarke, who said he had voted Republican in the past, published a book this week claiming that the Bush administration failed to take the terrorist threat as seriously as it should have before September 11, 2001.

After the terror attacks the administration pursued what Clarke called an unnecessary Iraq war to topple Saddam Hussein -- which "undermined" any war against the al-Qaeda terror network and the search for its leader, Osama bin Laden.

Clarke's book, "Against All Enemies," triggered a barrage of return fire from the White House and senior Republicans.

Several Bush staffers, including Vice President Richard Cheney, national security adviser Condoleezza Rice and White House spokesman Scott McClellan, questioned Clarke's credibility, saying he sought to promote book sales.

Rice told reporters that Clarke's book is "180 degrees from everything else that he said."

She refused to testify before the September 11 commission publicly, but agreed to do so privately for a second time.

Republican lawmakers said Friday that they would declassify Clarke's congressional testimony from July 2002, which they said belies his claims.