Vying to go where no New Jersey Republican has gone in 36 years - to the U.S. Senate - the three GOP candidates yesterday highlighted their differences on Iraq, immigration, diplomacy and national security.

In a televised debate in Trenton, former U.S. Rep. Dick Zimmer, State Sen. Joseph Pennacchio, and college professor Murray Sabrin each portrayed himself as a tight-fisted fiscal conservative best able to take on the Democratic nominee in November.

In the run-up to the June 3 primary, the GOP candidates are fighting not only each other, but also a lack of name recognition among voters and their party's chronic status as also-rans in Senate races.

Zimmer, a Washington lobbyist who has the state party organization's backing, tried to deflect attacks from Sabrin and, especially, Pennacchio, while presenting himself as the sensible choice.

Pennacchio, a Morris County dentist, repeatedly attacked Zimmer for his role as a lobbyist and for taking agricultural tax breaks on his 23-acre farm in Hunterdon County. He made energy independence and reduced spending the centerpieces of his platform.

Sabrin, a finance professor at Ramapo College, dubbed himself "Maverick Murray" and showed glimpses of his Libertarian past: He promised to visit Cuba, oppose foreign intervention, chop the size of government, and rein in the Federal Reserve.

All the candidates opposed government-provided health-care insurance.

On Iraq, Sabrin said he would set a September 2010 deadline for removing all U.S. combat troops. "I don't want to see any more killing," Sabrin said. "We've had enough war and destruction for the past 100 years. There's nothing wrong with negotiation."

Zimmer said the U.S. should "withdraw as quickly as we can" without setting a timetable. Leaving too soon or setting a timetable, he said, "could leave the region in chaos," and it "could become a haven for terrorists."

Pennacchio also opposed any timetable, but he said the Iraqi government had to understand that "our blood, our patience and our treasury are not unlimited."

On illegal immigration, Zimmer said "serious sanctions" against employers of illegal aliens would end the lure of jobs and prompt most illegal immigrants to leave the United States voluntarily.

Sabrin said the United States should end its long-standing "birthright citizenship" that conveys automatic citizenship to anyone born in the country.

Pennacchio said immigrants must be self-sustaining and not a drain on U.S. resources.

On the tension between national security and personal liberties, Sabrin came down on the side of personal freedoms, Pennacchio on the side of national security, and Zimmer said he'd try to balance the two.

Sabrin ran as a Libertarian candidate for governor in 1997. He lives in Bergen County.

Zimmer ran for U.S. Senate in 1996, losing a nasty and expensive campaign to Democrat Robert G. Torricelli. Zimmer, now a lobbyist for Gibson, Dunn & Crutcher of Washington, lives on a small farm in Delaware Township, Hunterdon County.

Pennacchio is serving his first year in the state Senate after four terms in the state Assembly.

None of the candidates is particularly well-known around the state, and the winner of the June 3 primary is expected to have an uphill battle against the Democratic nominee. No New Jersey Republican has won a U.S. Senate seat since 1972.

Zimmer, a state legislator from 1982 to 1991 and a member of the U.S. House from 1991 to 1997, has the most name recognition and the backing of the state GOP establishment.

Zimmer was ahead in a Monmouth University poll taken late last month, when he was favored by 25 percent of Republican voters polled. Pennacchio got 5 percent and Sabrin 4 percent of the support in the poll of 803 adults, with a margin of error of 3.7 percentage points.

More than half of Republican voters did not recognize any of the candidates' names.

The Republican race has had trouble gaining traction because the party lost its first two organization-endorsed candidates, as millionaires Anne Evans Estabrook and Andy Unanue dropped out.

Estabrook quit after suffering a minor stroke. Her successor, Unanue, bailed out after three weeks under fire for not living in New Jersey and for a drunken-driving conviction.

Last night, Sabrin and Pennacchio ridiculed the Monmouth University poll as statistically meaningless. Zimmer said he was glad to be seen as the front-runner but took "no comfort" in the poll.

Zimmer acknowledged that he "didn't anticipate being a candidate," but he said that his track record in Washington showed he could be a leader there, and that Democratic incumbent Sen. Frank Lautenberg "is vulnerable."

Lautenberg faces a challenge in the Democratic primary from U.S. Rep. Robert E. Andrews of Camden County. The senator's age is an issue: The 84-year-old Lautenberg would be 90 at the end of the new term he seeks, and polls have shown voters concerned that he may be too old to serve another term.

Contact staff writer Paul Nussbaum at 215-854-4587 or pnussbaum@phillynews.com.