Senate Armed Services Committee Chairman Sam Nunn revealed Tuesday that investigators were probing new allegations about John Tower even as the Senate debated his nomination to be defense secretary.

Though Nunn would describe the allegations only as more of the same that have dogged Tower's personal and professional history, Senate Republican leader Robert Dole said they involved the American Airlines Admiralty Club in Dallas, implying they were additional accounts of Tower's drinking habits.Tower, a former Texas senator, has been defending his nomination against questions of alcohol abuse to little apparent avail as most of the Senate's Democratic majority has indicated plans to vote against his confirmation.

Nunn said Tuesday, "We have gotten three or four new allegations from people that give their names, their addresses, their phone numbers, the details of a particular situation - and the question is to (my) committee, do we say, `No, we're sorry, we cut off all investigations'?"

The influential Georgia Democrat went on to say that because his committee had finished with the nomination, he had asked staff members of the Permanent Subcommittee on Investigations of the Senate Government Operations Committee to look into the matter. Nunn also chairs that subcommittee.

At Nunn's request, Senate leaders debated whether to close the door on the Tower case and to call off the subcommittee staffers or whether to ask the White House to involve the FBI once again in allegations against Tower. Nunn said the FBI had told him it was no longer involved in the nomination.

Sen. Arlen Specter, R-Pa., then told Nunn that White House counsel C. Boyden Gray had informed him both the White House and FBI would "be glad to follow up on any new allegations if asked to do so."

Nunn responded, "You've told me something I didn't know today. I've been told by the FBI that the White House told them not to pursue anything further. Now if that's not the case _ the FBI's still in business and the Senate decides that's the way to proceed _ I'll be the first to say let's move back."

Dole termed the matter "highly unusual, highly unprecedented," and complained to his colleagues, "We're making our case of fairness and unfairness. I don't see anything fair to Senator Tower in this effort."

At the White House, President Bush also defended Tower again, saying, "I want him. I believe he is the best man for the job."

Bush told a news conference he was sure Tower would "measure up" to a recent public pledge to quit drinking if confirmed, noting there are "25,000 people in the Pentagon making sure of that."

Tower's dim hopes got a boost Monday when Sen. Howell Heflin, D-Ala., said he would credit Tower's pledge _ and so became the first Democrat to cross party lines to declare he would vote for the nominee.

Senate Democratic leader George Mitchell of Maine said Tuesday he did not know how many Democrats might join Heflin in support of Tower but, "I do not believe they will be in numbers sufficient for confirmation." Mitchell said he hoped the vote could come "as soon as possible, certainly this week."

The sweetness of winning over Heflin's vote, savored publicly by Republicans, was soured a bit when the No. 3 man in the Democratic leadership, Sen. David Pryor of Arkansas, announced he would vote against Tower.

Republicans are outnumbered in the Senate 45 to 55.