Many New Jersey residents work across the state line in New York city, and so will be familiar with Democratic New York Senator Hillary Clinton and former Republican New York Mayor Rudy Giuliani.

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

Mrs Clinton is riding high in New Jersey opinion polls on the back of this "home-state" factor.

But as in New York's own primary, Mrs Clinton's results in New Jersey will be closely examined for any signs that they have not lived up to expectations.

Like Mrs Clinton, Mr Giuliani also held a strong lead here throughout 2007.

But after a succession of poor results in the early primary states, he is now trailing behind John McCain in New Jersey opinion polls. A defeat here, as in neighbouring New York, would sound the death knell for his campaign.

New Jersey is a densely-populated, heavily-industrialised state and voters here will be keen to find out what the candidates have to say about job creation.

Many New Jersey residents lost their lives on 11 September 2001, so security is also a key policy concern.