Key Senate Republicans rejected yesterday President Clinton's plea that they join him in negotiating a "reasonable" and "proportionate" response to House impeachment charges that would allow him to avoid a trial in the Senate.

But a consensus appeared to emerge among senators of both parties that while a Senate trial is almost certain to begin within a month or so, the proceedings may be cut short by a deal because the 55 Republicans don't have the two-thirds majority necessary to convict Clinton in the 100-seat chamber.

New polls show most Americans opposed Clinton's impeachment by the House Saturday on charges stemming from his relationship with Monica Lewinsky, and two-thirds of those surveyed believe he should remain in office.

But Republicans contended that they have a constitutional duty to conduct a trial and that, once it begins, it could be completed quickly, within weeks. Clinton would be to blame if the proceedings drag out, they said.

Democrats countered that the president has a right to defend himself and that a trial could take up to five months -- with the Republicans to blame for bringing the federal government to a standstill in an unpopular drive against the twice-elected Democratic chief executive.

Perhaps the most reliable prediction came from Sen. Arlen Specter, a Pennsylvania Republican, who said nothing can be taken for granted in the highly charged political atmosphere that has already toppled two Republican House leaders.

"When this trial starts, anything can happen, and I think that already we've seen so many turns and twists in the road, and I think we're going to see a lot more," Specter said on the CBS program "Face the Nation."

"While resignation is not realistic today, a plea bargain where he'd leave office is not in the cards today, stay tuned," Specter said.

Yesterday's comments reflected the confusion of a groggy morning-after following the nation's second presidential impeachment.

The impeachment votes that came almost exclusively along party lines in the House present a delicate political problem in the Senate, which usually can function only with bipartisan agreement. A Senate minority -- sometimes one senator -- can freeze any action.

Don Nickles of Oklahoma, the Senate majority whip and second-ranking Republican, took the hardest line among more than a dozen of his colleagues making television appearances yesterday, dismissing the notion of circumventing a Clinton trial.

"The Constitution says if you receive these articles [of impeachment], you will have a trial," Nickles said on "Fox News Sunday."

If the 45 Democratic senators were unified in their desire to avoid a trial and able to persuade six Republicans to join them, the trial "could be circumvented," Nickles said. "But I would be very surprised."

Sen. Orrin G. Hatch of Utah, who has already lost favor with his GOP colleagues lately for appearing sympathetic to Clinton, argued on NBC's "Meet the Press" that Republican leaders should consider whether conducting a trial is in the "best interests of the country" if it's already clear that Clinton won't be convicted.

But Nickles said the likely outcome shouldn't be a consideration.

"Let's get the facts out quickly," Nickles said. "And if he's not going to be convicted, so be it."

Rules Committee Chairman Mitch McConnell of Kentucky, who, like Nickles, reflects the views of the conservative Republicans driving the impeachment process, similarly dismissed the notion a speedy plea bargain.

"At some point on down the road, the solution that [Clinton and Democratic senators have] suggested may well be where we end up, but I don't see any constitutional alternative to going forward," McConnell said on "Meet the Press."

McConnell said it might also be possible to spare the country from potentially lurid testimony from Lewinsky and other witnesses by shutting off the television cameras and retreating into closed sessions.