The governor's race is the top ticket on the ballot. The Democratic Party also has a contested primary, but Jeff Boss, Carl Bergmanson and Roger Bacon have not been able to mount major campaigns against deep-pocketed incumbent, Gov. Jon S. Corzine.
Both parties also have primaries for seats in the state's General Assembly, though many are not contested; there are primaries for two special elections in the state Senate, but only one of them is contested. There are also races for municipal and county posts across the state.
Only members of a party can vote in the primary, but unaffiliated voters can register with parties on Election Day and still take part.
In 2005, turnout was a little under 580,000 - or 12 percent of all registered voters. It's been 20 years since as many as one-fifth of the state's eligible voters cast ballots in a gubernatorial primary. Going back to 1925, there has never been more than 39 percent participation.
Political analysts think that if turnout is very low, it could make for more drama as results roll in Tuesday night.
The latest polls show most likely voters had made up their mind, and supporting Christie by a wide margin over Lonegan, with Merkt running a distant third.
If Lonegan has any advantage, it's die-hard supporters.
"The supporters that he has are only committed to his candidacy and they're going to turn out one way or another," said Joseph Marbach, a Seton Hall University political scientist.
Meanwhile, Christie's support comes largely from Republican loyalists.
Unfortunately for Lonegan, the number of votes to make him a contender might have to be abnormally low.
After last year's surge of new voters drawn into the presidential race, New Jersey now has about 5.2 million voters, nearly half of them unaffiliated with a party. Just over 1 million are registered Republicans - about 150,000 more than there were in 2001 and 2005.
In both other Republican gubernatorial primaries this decade, more than 300,000 votes were cast.
"Two hundred fifty-thousand is going to be a magic threshold," said Ben Dworkin, a political scientist at Rider University. "If it is below that number, then Steve Lonegan has a better shot of winning."
Ingrid Reed, who directs the New Jersey politics project at Rutgers University's Eagleton Institute, said she'll be watching to see whether Lonegan can also get a boost from some General Assembly primaries.
Christie has the support of the main Republican organizations in each county, but nine of the 21 contested Republican primaries include candidates on Lonegan's slate.
Montclair State University political scientist Brigid Harrison said the Republicans have been overmatched lately in terms of organizing get-out-to-vote pushes in a state that has become more reliably Democratic.
But both Lonegan and Christie have major efforts heading into Tuesday.
Christie has a "Take Back New Jersey" bus tour crisscrossing New Jersey. He's also been drumming up volunteers to work shifts through Tuesday to call on supporters to vote.
Lonegan's tour - optimistically called the "Victory Lap" - had scheduled stops in every New Jersey county between Friday and Monday.
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