The bitter presidential election has New Yorkers registering to vote in unprecedented numbers. While Senator Kerry has the state’s 33 electoral votes all but sewn up, the new voters could tilt four tight state Senate races to the Democrats.

For the first time in its history, New York is likely to have 95% of its 13.5 million eligible voters registered to vote, according to a spokesman for the state Board of Elections, Lee Daghlian. That surpasses the 82% registration rate in 2000 and the 75% rate in 1996.

Counties won’t finish reporting their registrations to the state until November 1, but Mr. Daghlian estimates that more than a million people are newly registered. Those new voters are predominantly enrolled as Democrats, he said, which could endanger Republican senators presiding over historically Democratic strongholds.

While no one expects the Republicans to lose their majority, currently at 37 seats to 24, the Democrats hope to capture a few of the contested GOP held seats in this election.

“Largely, the new voters are younger, and many of them are in areas where there are large numbers of immigrants,” one political consultant, George Arzt, said. “What you’ve seen are areas that were thought to be somewhat asleep come to life.”

That should have a big impact on the Senate race in East Harlem and the South Bronx, areas with large Dominican and Mexican populations. The race pits a 13-term Republican, Olga Mendez, against Jose M. Serrano, son of Rep. Jose E. Serrano.

Ms. Mendez switched from Democrat to Republican the month after she last won re-election. In joining the party in power in Albany, she is depending on her status as an East Harlem institution to keep her in office. Her heavily Democratic district, however, is made more so by the newly registered voters.

“There was very big voter registration push made by the Democratic Party in that area,” another consultant, Norman Adler, said.

Ms. Mendez and a Westchester County incumbent Republican, Nicholas Spano, can take comfort in the fact that, of incumbents in New York’s legislative races since 1970,The New York Sun calculated, fully 98% won.

Mr. Spano has spent 18 years in the Senate leading a district that has 30,000 more registered Democrats than Republicans. New registrants can erase 1034 1158 1090 1169some of any incumbent’s advantage, however, since they’re not familiar with his work, and Mr. Spano’s Democratic opponent, Andrea Stewart-Cousins, will try to persuade these clean-slate Democrats to vote for her. Another potential problem for Mr. Spano, a member of the Senate leadership, and other incumbents this year is the rising tide of frustration with what is seen as political paralysis in Albany.

Many of the new voters in New York registered with forms printed out from Web sites such as MTV. comand MoveOn.org – thousands, according to Mr. Daghlian. Another recent Web registration drive by the state university system rounded up more than 12,000 new voters. With so many young people newly registered, races in areas with large college populations, such as Syracuse and the north Bronx, could be swung by the younger voters.

The guilty plea this year of another longtime Republican incumbent, Guy Velella, in a bribery scandal put the horseshoe-shaped Senate district in Yonkers and the Bronx up for grabs. Fordham University students could be the difference-makers in the three-way fight among the Democrat, Assemblyman Jeffrey Klein; the Republican, John Fleming, and the Conservative and Independence nominee, Assemblyman Stephen Kaufman.

The Orangemen of Syracuse could end up unseating maverick incumbent Nancy Lorraine Hoffman. Republicans hold a slight plurality in Onondaga County, which encompasses Ms. Hoffman’s district and the city of Syracuse. Democrats have already matched the 96,705 registrants they had in 2000, however, while the Republicans are still 4,000 behind their total. With a Conservative Party candidate siphoning off some of Ms. Hoffman’s support, the Democrat, David Valesky, may have an opening to capture the seat.

“We will be working to get our voters to the polls,” Mr. Valesky’s campaign chief, Joe Shafer, said. “Dave is going door to door. We’ll be giving rides to the polls.”

Turnout is the main concern for Democrats looking to improve their standing in the state Senate.

A researcher for the Manhattan Institute, E.J. McMahon, said Democratic enrollment has been growing for a decade, ever since the “motor-voter” laws allowed drivers to register when they renew their licenses. He said the Republicans’ greatest threat is not from Democrats but from themselves.

“Republican turnout upstate has been fairly poor in recent cycles,” Mr. McMahon said. “The base has nothing to get excited about. Any half-informed Republican voter in New York knows his or her vote does not count at the presidential level.”

Of course, with Mr. Kerry said to be in firm control of the electoral votes and Senator Schumer virtually assured victory in the U.S. Senate, there may be little reason for Democrats to turn out either. There’s also the possibility that the newly enrolled Democrats will be “bullet voters,” meaning they vote for the president and no one else.

Presidential races also bring out “every four years” voters. Those voters and the newly registered voters “tend to be very unsophisticated politically, very ill-informed about other levels of government,” besides the presidency, Mr. Adler said.

“They come out for the acrobats,” he said, “but they don’t stay to see the clowns.”