With close presidential aides saying that Mr. Clinton will reveal he had an "improper" relationship with Lewinsky, political pundits and players are debating whether this acknowledgement may lead to impeachment.
After seven months of denials, Mr. Clinton will face prosecutor Kenneth Starr in the first criminal investigation of a sitting president. Starr is trying to determine whether the president had a sexual relationship with Lewinsky, then tried to cover it up.
"I think that it is an impeachable offense," former federal judge Robert Bork told CBS's 'Face The Nation' Sunday.
However, Bork said he doubted that Mr. Clinton's presidency was in danger.
"I also think the Congress hasn't got the stomach to impeach as long as the president's approval ratings remain high," Bork said. "I think the Republicans won't do it."
Former White House counsel Lloyd Cutler echoed Bork's evaluation of Mr. Clinton's position.
"I don't think it's legally permissible under the Constitution to indict a sitting president, and it would certainly be most unwise, even for a special prosecutor, because imagine the country for the next two years with the president under indictment, and all of the things the president has to do," Cutler told CBS News.
Senate Judiciary Chairman Orrin Hatch -- in what looked like a clear attempt to influence Mr. Clinton's testimony decisions -- sent a strong signal Sunday that, if he admits to a relationship with Lewinsky, Republicans won't use it to start an impeachment bandwagon.
"If all that's involved here is the president lying under oath -- which is terribly serious -- but to protect his wife and his daughter from, at least trying to protect his wife and daughter from serious pain, you know, the American people, I think, will be willing to wait until the year 2000 to replace him," Sen. Hatch, R-Utah, said on NBC's Meet The Press.
A Republican on the House Judiciary Committee, which would handle any impeachment case, said the president's testimony in the Paula Jones case in which he denied a relationship with Lewinsky, could bring him trouble.
"If those of us sitting on judiciary conclude that indeed he did not tell the truth under oath in a court proceeding, or encouraged others not to tell truth or in some way obstructed justice, it would seem to me it would be very difficult not to vote to encourage and recommend impeachment," said Rep. Bill McCollum, R-Fla., who is a member of the House Judiciary Committee.
Whatever the president tells the grand jury, his advisers will be riveted on public opinion. The public has shown slight interest in impeachment up to now, and it won't take long to tell if that attiude has changed.