The fight for Florida's electoral votes shifts to a Miami courtroom today, with each side digging in its heels over a manual recount of presidential ballots.

Texas Gov. George W. Bush, whose minuscule lead in Florida has been shrinking to below 300 votes as more ballots are recounted by hand, is asking the federal courts to rule that the state's election law is unconstitutional and call a halt to further recounting.

U.S. District Judge Donald M. Middlebrooks, a Clinton appointee, has scheduled a hearing for this morning on Bush's request for an injunction to stop manual recounts in four heavily Democratic counties. Vice President Al Gore's camp sought the new tallies in hopes of turning up more votes for him.

Representatives of both presidential candidates trod the television talk show circuit yesterday, while officials in one Florida county, Volusia, began the tedious job of recounting 185,000 ballots by hand.

Gore's campaign drew encouragement from a preliminary hand count in Palm Beach County, where officials decided about 2 a.m. yesterday to manually count all of the votes cast in Tuesday's election - some 470,000 ballots. Gore narrowed Bush's already-slender edge in a test examination of ballots from four Palm Beach precincts, representing about 1 percent of the vote cast, over the weekend.

Statewide, Bush's advantage over Gore has shrunk to 288 votes, according to the latest Associated Press count. The official total by the office of Florida's secretary of state shows Bush 960 votes ahead but does not include returns from Palm Beach County.

Yet to be counted are an undetermined number of overseas absentee ballots, which must be received by Friday. That is the earliest date that an answer might be found to the pivotal question of which presidential candidate carried the Sunshine State, though it could well take longer.

Neither side is ruling out the possibility that all 6 million ballots in Florida could wind up being counted manually before it is over in the state, whose 25 electoral votes will likely decide the next president.

Nationally, Gore leads Bush by 216,000 votes. His campaign continues to call him the winner in the popular vote, though it will take several weeks before all ballots are counted.

The vice president is also clinging to a 255-246 electoral vote advantage over the Texas governor in the race to the 270 needed to win. Besides Florida, the results are not final in Oregon, with seven electoral votes, where Gore leads by less than 6,000 votes, and in New Mexico, with five electoral votes, where Bush was ahead by 17 votes.

Based on the slow progress of the initial hand count in Palm Beach County - it took almost 10 hours to count 4,600 ballots - it could take days to count all the votes by hand in the state's largest counties.

In Miami-Dade, officials plan to decide tomorrow whether to grant the Democrats' request for a recount of more than 620,000 ballots. Volusia County will go to state court today to request an order allowing the count there to continue beyond the deadline of 5 p.m. tomorrow, when all counties are supposed to certify their results.

However, officials in Volusia, which includes Daytona Beach, expressed optimism last night that their hand count might be finished as early as this evening. Manual recounts were completed yesterday in almost half the county's 172 precincts.

Around the country, senior figures from both parties continued to stress the need for closure and urged Bush and Gore to put the national interest ahead of their own ambitions.

Former Sen. Sam Nunn of Georgia, a Democrat, issued a statement urging both men to act "in a manner worthy of the office they seek."

Nunn said Gore "should make it clear that he would concede the victory to Governor Bush if he loses Florida after the more scrupulous recount and the counting of the absentee ballots."

Sen. John McCain, an Arizona Republican, said "litigation is not the answer" and that both sides should agree to let Florida's results decide the election.

The Bush campaign is preparing to request recounts in states where Gore leads or appears to have won by a narrow margin, including Wisconsin, Iowa and Oregon.

The Republican point man in Florida, former Secretary of State James A. Baker III, reiterated Bush's offer to drop his lawsuit in federal court if the Gore campaign would agree to abandon its request for hand recounts and abide by the official total in the state when the overseas absentee ballots are counted.