In speeches on Monday and Tuesday, two top officials, including the attorney general, will seek to make the case that the president has the constitutional authority to let intelligence officials listen in on international phone calls of Americans with suspected ties to terrorists.
President Bush joins in Wednesday with a visit to the super-secret National Security Agency, which on his orders conducted the eavesdropping.
The administration wants to persuade Americans that the NSA authorization is a "vital tool" to detect and prevent attacks on the U.S.
"We are stepping up our efforts to educate the American people," White House press secretary Scott McClellan said about Mr. Bush's trip to the NSA, based at Fort Meade in Maryland.
"This is a critical tool that helps us save lives and prevent attacks," he said. "It is limited and targeted to al Qaeda communications, with the focus being on detection and prevention."
On Monday, deputy national intelligence director Mike Hayden, who headed the National Security Agency when the program began in October 2001, will speak on the issue a the National Press Club.
On Tuesday, Attorney General Alberto Gonzales is delivering a speech on the program in Washington.
Gonzales plans to testify publicly about the secret program at a Senate hearing set to begin Feb. 6.
Gonzales said he reached an agreement with Sen. Arlen Specter, R-Pa., chairman of the Senate Judiciary Committee, to answer questions about the legal basis — but not the operations — of the NSA's warrantless eavesdropping on telephone conversations between suspected terrorists and people in the United States.
Gonzales this week sent congressional leaders a 42-page legal defense of warrantless eavesdropping, expanding on arguments that he and other administration officials have been making since the program was first disclosed last month.
The memo argues that Mr. Bush has authority to order the warrantless wiretapping under the Constitution and the post-Sept. 11 congressional resolution granting him broad power to fight terrorism.
Vice President Dick Cheney, who was to meet with congressional leaders at the White House on Friday to discuss the issue, defended the program on Thursday in New York in a speech to the conservative Manhattan Institute. He stressed that the program was limited and conducted in a way that safeguards civil liberties.
At a briefing held by House Democrats on Friday, the American Civil Liberties Union called the program an illegal operation.
"The executive power of our country is not an imperial power," Caroline Fredrickson, the director of the ACLU legislative office in Washington, told Democratic members of the House Judiciary Committee.
"The president has demonstrated a dangerous disregard for our Constitution and our laws with his authorization for this illegal program," she said.
Fredrickson spoke to Democratic members of the House Judiciary Committee. The ACLU filed suit against the NSA on Jan. 17 on behalf of journalists, nonprofit groups, terrorism experts and community advocates. The suit alleges that the NSA program violates the First and Fourth amendments and the separation of power.