President Bush deserves credit for being more candid recently about the war in Iraq and the broader campaign against terrorism. In a nationally televised speech Sunday, and in a news conference Monday, he acknowledged some frustrations and difficulties, and he made a credible case for continuing the campaign to establish a free government in Iraq.

But not everything he said was as convincing. On the issue of domestic spying without a warrant, his reasons and his justifications remain murky, at best.

The president would have Americans believe that Congress authorized him to tap into the phone calls and e-mails people in America send overseas when it authorized him to fight terrorism before the war in Afghanistan. He said Monday that the Constitution grants him the authority to approve such spying, but he never elaborated as to exactly where in the Constitution such authority is granted.

The issue here is not so much whether the federal government should be allowed to listen in on communications it suspects involve terrorist plots. Clearly, the government has a duty to protect national security, and it has a right to obtain vital information that aids in performing that duty.

No, the issue has to do with following the process that is in place to protect the American people from abuses by a president and his investigators. The Foreign Intelligence Surveillance Act allows the government to wiretap in defense of national interests. But it also sets up a special secret court, available on a moment's notice, to hear the government's pleas and to grant a warrant for such searches.

That safeguard is a necessary check on power. Otherwise, the president would have absolute authority to spy on Americans as he pleases.

President Bush says obtaining warrants would unnecessarily slow down a process that demands speed and agility. Given the nature of the secret FISA court, however, that is not a convincing argument.

The nation's founders passed the Fourth Amendment to the Constitution in response to abuses they had faced at the hands of a British government that could search homes and property with impunity. The amendment says simply that, "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated É" It then goes on to say that searches can be conducted only through warrants issued "upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."

Perhaps the president feels the American people will side with him on the need to bend these safeguards in the war on terrorism. But enemies of the state have existed in the midst of American society virtually from the beginning, and certainly in each of the last 100 years. That hasn't kept law enforcement from having to obtain warrants.

Americans should indeed support the president in his continuing efforts in Iraq. Given what is at stake, failure should not be an option, and an early withdrawal would lead to failure. The war on terror within this country, however, must conform to reasonable checks on presidential authority.