At first glance, it does seem contradictory. New Yorkers consistently send Democrats to represent them in Albany and Washington, but they've also elected a Republican as mayor three times in a row. And George Pataki's strong showings in the city combined with his upstate margins got him elected governor three times.

It's not that New Yorkers are schizophrenic - it's that they're shrewd. They elect Democrats to fight for other people's money, but prefer to have Republicans manage their own.

At the local and community level, this is truly a one-party town: Democrats control 48 of the City Council's 51 seats, 11 of 12 congressional seats, 21 of 26 state Senate seats and all but two of the 64 Assembly seats.

But when it comes to managing the city's $47 billion budget and keeping streets safe, New Yorkers no longer seem comfortable turning government over to Democratic politicians beholden to unions and clubhouses.

Clearly, it's a mistake to confuse Democratic strength in numbers with strength as a party. Several developments have changed the old patterns and given Republicans openings when they play their cards right.

Start with the fact that this is now a city with millions of immigrants not tied to traditional Democratic politics and willing to support Republicans for mayor. Next, add in the fact that ever since Robert Wagner won his third term as mayor in 1961 by running against his own party's bosses, the so-called Democratic machine has been in turmoil.

The most powerful present-day Democratic leader, Tom Manton of Queens, controls judicial elections but has consistently supported mayoral losers: Richard Ravitch in '89, Fernando Ferrer in '97, Alan Hevesi in 2001.

Republicans also benefit from the Democratic tendency to nominate candidates who mobilize hard-core liberals in the primaries but can't attract moderates in general elections.

And Republicans have one solid political base, Staten Island. It's true that they are outnumbered by registered Democrats there, but they are highly organized and know how to turn out their voters. It's the only borough where there is a competitive two-party system.

Finally, by nominating fresh faces like Rudy Giuliani and Mike Bloomberg, who earned their credentials without previously holding elective office, Republicans have built coalitions that crossed party lines and appealed to the fastest-growing segment of the electorate: independent voters, who now number 670,000.

Still, to win in New York, Republicans must break with their own national party on many key points. Candidates cannot win citywide office unless they support abortion rights, gay rights and pro-immigration policies, positions at odds with the modern GOP.

This local-national split has cost the Republicans dearly in presidential elections in the city (as opposed to the state, where they've done reasonably well over the years). The last Republican presidential candidate to carry the city was Calvin Coolidge in 1924. Even a genuine war hero like Dwight Eisenhower, who had served as president of Columbia University and had the support of Harlem Democratic Rep. Adam Clayton Powell in his 1956 reelection bid, could not win here.

If the Republicans arriving here for the convention want to see their party make gains in Democratic strongholds like this one, they must moderate their ideological positions, just as successful New York mayors have done for the past decade.

Moss is Henry Hart Rice professor of urban policy and planning at New York University.