New Jersey will be among 24 states holding presidential primaries or caucuses that day, which could prove pivotal in deciding closely fought presidential campaigns for both Democrats and Republicans.
Here's a look at some questions and answers about the first presidential primary in New Jersey that will be consequential since 1980, when New Jerseyans supported Edward Kennedy over President Carter in the Democratic primary:
Q: What is a primary?
A: Primary elections choose a political party's candidates for office. New Jersey voters will decide only presidential candidates on Feb. 5. Primary elections for all other offices - this year U.S. Senate, House of Representatives, county and municipal races - will be held in June.
Q. Why did New Jersey move its primary?
A. It's trying to make itself more relevant in choosing presidential candidates. Its June primary has typically left it with no real say in choosing candidates because the nominations were sewn up after the primaries held earlier by other states.
Q. Has it worked?
A. Candidates have visited the state to campaign and raise money, but not frequently. New Jersey is competing with 24 other states that are holding contests that day, the earliest date the parties would allow other contests beyond traditional early races in Iowa, New Hampshire, Nevada and South Carolina.
One factor that might have kept candidates away are polls showed Democrat Hillary Clinton and Republican Rudy Giuliani with huge leads in the state. But a Tuesday poll showed John McCain and Giuliani even, and a competitive race might bring more visits.
Q: Who can vote in the Feb. 5 primary?
A: In New Jersey, only registered Democrats and Republicans can vote in their party races. People who are registered but unaffiliated must choose a party at the polls if they wish to vote.
The state has about 4.8 million registered voters, of which the largest chunk - 2.8 million - aren't affiliated with any political party.
Q: What time are polls open?
A: 6 a.m. to 8 p.m.
Q. Where do I vote?
A. Your normal polling place. If unsure, check with your county boa
Q: What's the expected turnout?
A: New Jersey voters historically show little interest in primary elections.
For example, the last presidential primary, in 2004, which also included U.S. House candidates, attracted only 9 percent of all registered voters. In 2000, a primary which had a U.S. senate race in addition to president and House, only 17 percent cast ballots.
However, those primaries were held in June, and no one is really sure what turnout will be for a February presidential primary when the race is competitive.
Q. Who's on the ballot in New Jersey?
A. For Democrats, Delaware Sen. Joe Biden, New York Sen. Hillary Rodham Clinton, Ohio Congressman Dennis Kucinich, Illinois Sen. Barack Obama, New Mexico Gov. Bill Richardson and former North Carolina Sen. John Edwards.
For the Republicans, the candidates are former New York Mayor Rudy Giuliani, former Massachusetts Gov. Mitt Romney, Arizona Sen. John McCain, Texas Congressman Ron Paul, former Tennessee Sen. Fred Thompson, former Arkansas Gov. Mike Huckabee.
Q. Didn't some of those candidates drop out?
A. Yes. Biden and Richardson are no longer running, but their decision came after New Jersey's ballot deadline, so their names remain on the ballot. People can still vote for them, but they'll be voting for candidates who aren't running.
Q. What are we voting for?
A. The winner of the Republican primary will receive all of the party's 52 delegates.
Of the state's 127 Democratic delegates, 70 will be distributed based on the candidates' share of the vote, while most of the rest are selected by the state party.
Delegates cast their votes at each party's convention in the summer.
Nationwide, a majority of 4,367 delegates are needed for the Democratic nomination, and a majority of 2,380 delegates for the Republican nomination.
Q. Who else is holding contests on Feb. 5?
A. Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Georgia, Illinois, Massachusetts, Minnesota, Missouri, New York, North Dakota, Oklahoma, Tennessee and Utah are holding Democratic and Republican contests.
Idaho, Kansas and New Mexico are holding Democratic contests.
Montana and West Virginia have Republican contests.
Q: How can I view results on election night?
A: Some county clerk and newspaper Web sites will post results and several television and radio networks will provide coverage.
Q. How can I register to vote for the primary?
A. It's too late. Jan. 15 was the deadline to do so. But there's plenty of time to register for the June primary, and the November general election.
Q. Do I have to show up at the polls to vote?
A. No. You can vote by absentee ballot. To do so, you must apply to your county clerk by Jan. 29 to vote by mail. If you fail to apply in writing for an absentee ballot within the seven day time frame, you may apply in person - or by an authorized messenger if you're sick or confined - to your county clerk up to 3 p.m. the day before the election.
Your absentee ballot must be received by your county Board of Elections no later than 8 p.m. on Feb. 5.
Q. In big elections like this, can candidates and their supporters lobby me as I go to vote?
A. Campaigning can take place freely as long the activity is at least 100 feet from the outside entrance to the polling place. The zone is usually marked by a flag.
Exit polling by the media within that 100 feet is permitted.
Q. What documents do I need to bring to vote?
A. You must show identification to vote at the polling place. Identification may include documents, such as a driver's license or student, job, military, government and store membership identification cards and a U.S. passport.
Q. Can I take my child in the voting booth?
A. Yes. State law allows voters to be accompanied into the voting machine booth by a dependent child.
Q. Where do I go for more information?
A. Visit http://www.nj.gov/oag/elections/electionshome.html.
