325,000 expected to vote Tuesday
The Democrats are having a primary, too, but it is a formality. Obama is not opposed in New Hampshire - or anywhere for that matter - by any significant challengers.
As a result, Secretary of State William Gardner expects only 75,000 to vote in that primary as opposed to 250,000 in the Republican primary.
Registered independents, officially called undeclared voters, can vote in either primary (not both), but voters who are registered in one party cannot vote in the other party's primary.
There are 30 Republicans and 14 Democrats on the New Hampshire Primary ballot, but as the GOP race comes to an end, the focus is on five men - Mitt Romney, Newt Gingrich, Rick Santorum, Ron Paul and Jon Huntsman.
Texas Gov. Rick Perry is also on the ballot, but, after a poor showing in the Iowa caucuses, he has bypassed New Hampshire to focus on the more socially conservative South Carolina, where Republicans will hold an important primary on Jan. 21.
► Click here for more pictures from Sunday morning's debate, as well as photos from the Primary campaign trail.
The only woman candidate, Minnesota U.S. Rep. Michele Bachmann, dropped out of contention following a poor showing in the Iowa precinct caucuses on Jan. 3.
She remains on the ballot, however, as does businessman Herman Cain, who dropped out of contention last month.
The GOP nomination race has developed into a multi-level contest. Former Massachusetts Gov. Mitt Romney has led in polling throughout the campaign, while other candidates have risen into second place temporarily, only to then fall.
Most consistently in second place in recent weeks has been the Libertarian-leaning Republican, Texas U.S. Rep. Ron Paul, whose unorthodox views, many say, render him ultimately unelectable.
Over the months, while Romney has remained steady atop the New Hampshire field, moving into second place at one time or another were Bachmann, businessman Cain, Gingrich and most recently, Paul.
While New Hampshire voters have long been shown to be unpredictable, it appears this primary will be, first, a race for second place to determine who is the alternative to Romney moving forward. It will also be a test of whether Romney can hold onto the high level of support he has had from Granite Staters throughout 2011.
If Romney fails to secure a big victory margin, it will be viewed nationally as a loss. A big New Hampshire victory will set up Romney as the strong favorite to win his party's nomination.
Former U.S. Ambassador to China and Utah Gov. Jon Huntsman has also moved up slightly in polling recently, as has former Pennsylvania U.S. Sen. Rick Santorum following his virtual tie with Romney in the Iowa caucuses.
Romney has been weathering charges by the other candidates and the Democrats that he is a 'flip-flopper.' The other Republicans have also questioned his support as Massachusetts governor for a health care plan that contained a mandate that most residents purchase health insurance. Dubbed 'Romneycare,' critics say it was the forerunner for the Obama-backed Affordable Care Act, dubbed 'Obamacare.'
Paul's controversy has stemmed from his belief that the United States has militarily overextended itself and should drastically contract its military. Unlike the other candidates, Paul says the United States should not challenge or confront Iran if the terrorist nation acquires nuclear weapons.
Gingrich says he is the only candidate who has actually cut spending and reformed government through the 'Contract With America' he championed as House speaker in the mid-1990s.
Santorum is attempting to focus on a blue-collar brand of economic conservatism, based on his roots in economically downtrodden western Pennsylvania. He has also touted his conservative credentials on social issues.
Huntsman says he is the most well-rounded candidate to become President, having served overseas as ambassador to China and as an effective governor. Huntsman has devoted his entire campaign to New Hampshire and did not campaign in other states.
Perry is focusing on his record in Texas as a budget balancer and jobs creator. He calls for a flat tax and has energy independence as the foundation of his economic plan.
A list of polling places for Tuesday's primary election is available at unionleader.com/polls