When it considers a fiscal 2009 intelligence authorization bill Tuesday, a Senate panel is likely once again to challenge the Bush administration’s authority to use harsh interrogation techniques on suspected terrorists.

The Senate Intelligence Committee’s markup of the draft legislation comes only days after Sen. Ron Wyden, D-Ore., released Justice Department letters that claim there could be fewer restrictions on the treatment of detainees if the administration believes it is acting to prevent a terrorist attack.

House Judiciary Chairman John Conyers Jr., D-Mich., threatened Monday to subpoena one current and two former Bush administration officials if they continue to resist testifying at a May 6 hearing on other Justice Department interrogation memos.

President Bush vetoed the fiscal 2008 version of the intelligence authorization bill (HR 2082) over a provision that would require all federal agencies, including the CIA, to comply with interrogation standards set in a September 2006 Army field manual. The standards prohibit military personnel from using tactics such as waterboarding, which simulates drowning.

At issue is whether brutal techniques are inhuman, ineffective and damage the United States’ international standing, as Democrats argue, or whether the manual’s standard is impractical for the CIA and would hobble its ability to gather life-saving intelligence, as Republicans argue.

The Intelligence Committee is expected to begin consideration with a draft 2009 version that does not include the interrogation language. Earlier versions had included expanded authority for the nation’s spy chief to shift personnel and adjust budgets, along with expanded congressional oversight powers, such as requiring Senate approval of several high-ranking intelligence officials.

But Dianne Feinstein, D-Calif., a member of the Intelligence Committee, has vowed to continue pressing for the interrogation language, which she successfully offered in the 2008 version.

“The CIA has heard the message that a majority in both houses of Congress want the uniform standard provided by the Army field manual,” she said the day before Bush vetoed the 2008 bill in March. “We will not stop until it becomes law.”

After the House failed to override the veto, Feinstein said, “We’ll just keep sending it back, and he can keep vetoing it.”

Intelligence Chairman John D. Rockefeller IV, D-W.Va., also has indicated that he would be willing to risk not getting an intelligence authorization bill signed into law in order to press the ban on harsh interrogation tactics.

“I am not going to put my party and my conscience in jeopardy by taking out” the interrogation language, Rockefeller said after Bush vetoed the 2008 measure. “They say you can take it out and pass it again, and [Bush would] sign it. Not me.”

The Justice Department’s letters to Wyden are likely to fuel Democrats’ commitment to include the interrogation language. In one letter dated March 6, Brian A. Benczkowski, a deputy assistant attorney general, argued that the Geneva Conventions’ “prohibitions on outrages upon personal dignity” may require case-by-case evaluation.

“The fact that an act is undertaken to prevent a threatened terrorist attack, rather than for the purpose of humiliation or abuse, would be relevant to a reasonable observer in measuring the outrageousness of the act,” Benczkowski wrote.

Democrats have been pushing back against the administration’s interrogation and detention policies on several fronts.

Conyers issued his subpoena threat in letters to David Addington, who is Vice President Dick Cheney’s chief of staff; John C. Yoo, a former deputy assistant attorney general in the Justice Department’s Office of Legal Counsel; and former Attorney General John Ashcroft.

Attorneys for all three men have cited executive privilege to avoid testifying. Conyers countered that officials and ex-officials in similar circumstances have testified in front of Congress before. He said they had until May 2 to reply or face subpoena.