The U.S. Supreme Court, its deep division on full public display, stopped the vote counting in Florida yesterday and set the stage for a ruling that could make George W. Bush the next president.

By a vote of 5-4, the court blocked a 22-hour-old ruling by the Florida Supreme Court that required new hand counts of presidential ballots. The justices' action immediately jeopardized Vice President Al Gore's chances of overtaking Bush.

The justices also agreed to hear Bush's challenge to the state decision. It set a hearing, to run 90 minutes, for 11 a.m. tomorrow - a sign of jeopardy for the Florida court's ruling.

One justice in the majority, Antonin Scalia, suggested that the action meant a majority believes that Bush "has a substantial probability of success" in his challenge.

The four dissenters in the case - aptly named George W. Bush vs. Albert Gore Jr. - also said that the court's action runs the risk of being "tantamount to a decision" in favor of Bush.

James A. Baker III, Bush's chief strategist in Florida, said the Texas governor was "very pleased" by the court's action but warned that the dizzying month of ups and downs was not over because the court has not ruled on the merits of the case.

Gore's lead attorney, David Boies, said he remained optimistic that the vice president would ultimately prevail but that the Supreme Court's action yesterday makes it "much more difficult" to complete the count by Dec. 12. That is the date by which Florida is supposed to finish picking its 25 presidential electors, enough to give either candidate the White House.

Bush's lawyers asked the court to stop the counting, saying it threatened to "imperil" his "proper receipt" of Florida's electoral votes and could wipe out his certified victory. Gore's attorneys resisted, arguing that Bush had suffered no legal harm from the counting and that if he did he could return to court with his constitutional challenge.

The Texas governor's statewide margin stood at 154 after the Florida Supreme Court ruling Friday afternoon. The two campaigns were in dispute about who had made gains during the recount yesterday before the Supreme Court brought it to a halt.

The Supreme Court agreed to hear the Bush appeal even before it had been technically filed. The court treated the Texas governor's "emergency application" for a temporary stop to the counting as if it were the appeal itself, and granted it, as Bush's attorneys had suggested in a one-sentence footnote.

All nine justices were at work at the court yesterday. They issued their order five hours after Gore's lawyers had filed their response to Bush's request for a halt to the count.

The vice president's legal strategists had not expected the court to do anything until after a formal Bush appeal was filed last night.

Both sides stressed that what the justices had done was not a final decision in the case. The possibility remained that, after hearing the case, the court might yet uphold the Florida Supreme Court ruling or else decline to disturb it - either of which would permit the counting to resume.

That outcome appeared to be a long shot. Even Gore's attorneys said privately, before the court acted, that their cause would be in considerable trouble if the court ordered a stop - even a temporary halt - to the counting. They conceded it would be a sign of the court's tilting toward Bush's ultimate claim that he would be harmed if the counting went on.

The immediate effects of the court's order were twofold:

In their attempt to salvage his candidacy, Gore's lawyers were down to 50 pages of legal writing, to be filed this afternoon, plus 45 minutes of oral argument tomorrow.

Bush's lawyers had the same space and time allotments to try to hold together a clearly sympathetic and controlling five-justice bloc - apparently an easier task.

If the court, in a final ruling that is expected after the hearing tomorrow or on Tuesday, strikes down the Florida Supreme Court decision, it probably would return the electoral situation in Florida back to Nov. 18 or Nov. 26.

On both days, Bush was ahead by a narrow margin, but enough - 930 votes on Nov. 18 and 537 on Nov. 25 - to make him the winner of Florida's 25 electoral votes, and with them, the presidency by one vote more than the simple majority of 270 that is required. Bush trails Gore in the electoral count vote by 267 to 246.