A key Democratic senator suggested Sunday that President Clinton immediately volunteer to testify before Congress to halt a "political water torture" that escalates this morning when Americans view raw footage of the president's grand jury testimony about Monica Lewinsky.

That video will show Clinton admitting "inappropriate intimate contact" and "sexual banter" with Lewinsky but resisting prosecutors' efforts to define the conduct further. Clinton offers many legalistic replies and, at times, shows remorse."I regret that what began as friendship came to include this conduct," the president answered when he was first asked a sex-related question by prosecutors just seven minutes into his Aug. 17 testimony. The president's testimony was described to The Associated Press by lawyers familiar with it.

The moments of presidential regret are interspersed with legal hairsplitting involving the terms "sexual relations" and "alone" and, in one exchange, the tense of a verb.

At one point, Clinton was asked why he failed to produce to Paula Jones' lawyers a series of correspondence between himself and Kathleen Willey, the former White House volunteer who accused the president of an unwanted sexual advance near the Oval Office in 1993.

Clinton replied that he understood the subpoena to cover personal documents, and the Willey letters were in White House files. If the lawyer wanted the letters, Clinton said, they should have issued two subpoenas - one personal and the other official, lawyers said.

The White House and Congress - both facing perils in the unfolding impeachment proceedings - braced for the release Monday of an avalanche of new evidence that includes more material in which Lewinsky explicitly describes sex acts with Clinton, the president's videotape, presidential phone messages left at Lewinsky's home and the FBI test results conducted on one of Lewinsky's dresses.

Clinton made a brief appearance Sunday morning at a fund-raiser aboard a Potomac River cruise ship, and then he and Hillary Rodham Clinton attended services at Foundry United Methodist Church, the first time since before his Aug. 17 grand jury testimony. On Monday, when the 2,800 pages of documents and videotape are released, Clinton will be in New York City

addressing the United Nations.

A key senator suggested on the Sunday talk shows that Clinton immediately volunteer to testify to the House Judiciary Committee and answer all questions fully to spare the country further embarrassment.

"I believe the president would be well-served to explain exactly what he did, exactly what he was thinking, do it to the JudiciaryCommittee and let's vote and let's move on one way or the other," said Sen. John Kerry a Massachusetts Democrat and Clinton ally.

"The nation is being ill served by this political water torture that is taking place in a highly calculated, highly partisan way," Kerry told NBC regarding Congress' selected release of evidence.

Kerry's call for voluntary Clinton testimony was embraced by several colleagues, including Republican Sen. John Ashcroft, a presidential aspirant and harsh Clinton critic, and House Judiciary Committee members Barney Frank, D-Mass., and Lindsey Graham, R-S.C.

Uneasy about defending some of Clinton's legalistic answers, Democrats are discussing whether to concede Clinton committed perjury and accept Lewinsky's ver-sion of their sexual encounters even though Clinton disputes her allegations that he touched her.

"I'm almost willing to say, `Let's stipulate that President Clinton touched Monica Lewinsky where he shouldn't have,' " Rep. Robert Wexler, D-Pa., said on NBC.

Two sources familiar with the material Starr turned over to Congress told the Associated Press it includes an FBI interview report of an Arkansas woman, 55, whom Jones' lawyers sought to question about possible sexual misconduct by the president two decades ago.

The sources, who spoke on condition of anonymity, said the FBI report is "inconclusive" about whether anything improper happened, declining to be more specific. The report is not among the materials scheduled for release today.

In an event unparalleled in history, the unfiltered footage of the president's grand jury testimony will be aired by cable news channels simultaneous with its release, expected shortly after the breakfast hour Monday. To prepare viewers, CNN aired special statements Sunday warning that the video, which it plans to run in its entirety, contains "both language and descriptions" that "may be offensive to some viewers and unsuitable to children."

Congress risked a political backlash by releasing a videotape that 52 percent of Americans said they planned to watch but that 69 percent felt was unnecessary to release, according to a CBS survey.

The CBS poll indicated Congress' approval rating had dropped from 56 percent earlier last week to 44 percent and that 59 percent of the public believed the tape's release had more to do with embarrassing the president than letting the public judge him. The White House sharpened its attack Sunday along those lines.

"They (lawmakers) decided that rather than just doing a document dump they would do a garbage dump on Monday, and I think people are going to wonder about that," White House deputy chief of staff John Podesta said.

Though only Clinton will be visible on the videotape, which was made as part of a closed-circuit TV feed from the White House map room to the federal court house, the public also will get its first glimpse of the conduct of Independent Counsel Kenneth Starr's prosecutors whose work has been conducted in the secrecy of the grand jury.

Four prosecutors can be heard posing questions to the president, frequently using graphic sexual terms and even starting off the entire question with a debate over the oath the president had just taken.

Lawmakers who already viewed the tape sought to lower expectations about its long-term political impact. "Frankly, large portions of it are rather boring," Rep. Asa Hutchinson, R-Ark., told ABC.

"If you like the president there are going to be times when you feel sympathy for him," said Graham, a conservative Republican. "If you think he is a guy you don't like there are going to be things you seize upon, but it is not going to be a knockout blow."

Rep. Marty Meehan, D-Mass., another House Judiciary Committee member, agreed: "I don't think it will have a great positive or negative effect," he told ABC.

At times combative and evasive, Clinton also lets his guard down on occasion during the testimony, according to one lawyer familiar with it.

At one point he spoke of the pain of having to acknowledge under oath in his Jan. 17 Paula Jones deposition having "sexual relations" with Gennifer Flowers, the Arkansas woman whose allegation of an affair nearly derailed his 1992 presidential bid.

He also expressed regret that Lewinsky, now 25, had been embroiled in the Starr investigation. He portrayed himself as a concerned friend who, after their sexual contact ended, still tried to help find her a new job and to help her avoid having to testify in the Jones sexual harassment lawsuit.

"I think he is very sincere, you can tell that this has hurt the guy," said Graham, a Republican who has seen the videotape.