A bipartisan group of senators and scholars denounced President Bush yesterday for using scores of "signing statements" to reserve the right to ignore or reinterpret provisions of measures that he has signed into law.

Bush's statements have challenged, for instance, a congressional ban on torture, a request for data on the administration of the USA Patriot Act and even a legislative demand for suggestions on the digital mapping of coastal resources.

The Senate Judiciary Committee's hearing marked the latest effort by Chairman Arlen Specter (R-Pa.) and panel Democrats to reclaim authority that they say the president has usurped as he has expanded the power of the executive branch. It came on the same day Bush gave a speech pushing for a line-item veto that would allow him to strike spending and tax provisions from legislation without vetoing the bill.

Other presidents have used signing statements to clarify their interpretation of laws, but no president has used such statements instead of ever using the veto authority spelled out in the Constitution, said Harvard University law professor Charles J. Ogletree Jr., who is serving on a new American Bar Association task force examining Bush's signing statements. Bush has never used his veto power in his presidency.

"There is a sense that the president has taken the signing statements far beyond the customary purviews," Specter told the administration's representative, Michelle E. Boardman, deputy assistant attorney general in the Justice Department's Office of Legal Counsel. "There's a real issue here as to whether the president may, in effect, cherry-pick the provisions he likes and exclude the ones he doesn't like."