Date of primary: 5 February [Super Tuesday] Election polltracker Full state profile Q&A: US primary elections

With a prominent New York politician in both the Republican and Democratic races, most commentators expected the results in New York's state primary to be foregone conclusions: former New York Mayor Rudy Giuliani would win the Republican contest and New York Senator Hillary Clinton would triumph in the Democratic primary.

But following Mr Giuliani's poor performances in the early primary states, while Mrs Clinton is still riding high in surveys of New York voters, the former mayor's poll lead has slipped and he now trails John McCain in the state.

If Mr Giuliani fails to win in New York, then his candidacy will almost certainly be over.

Because Mrs Clinton is such a favourite to win here, experts will be examining her margin of victory very closely - a narrow win in New York could be as damaging to her campaign as a loss in another state.

The candidates have not been spending heavily in New York, although Mrs Clinton has aired some campaign advertisements in the state.

The state - one of the wealthiest in the US - is the source of much of the candidates' funds, however.

New York state is, of course, dominated by New York city, but the state also has large rural areas.

The majority of voters in the state are on the liberal end of the political spectrum and security is a key issue for many residents in light of the 9/11 attacks.