NEWARK — Visibly angered by weeks of negative campaign fliers and a new television ad attacking him, Jack Ciattarelli repeatedly fought back against his opponent in the Republican primary for New Jersey governor Thursday night, criticizing Kim Guadagno’s plans for auditing the state government and questioning her political tactics in a fiery debate defined by interruptions and accusations.

Mr. Ciattarelli, a state assemblyman, challenged the Guadagno campaign’s integrity, accusing his opponent, the lieutenant governor, of promoting falsehoods about his record and of lying about her own. Within the first five minutes of the debate, Mr. Ciattarelli denounced Ms. Guadagno’s plan to reduce property taxes as disingenuous, claiming that “quite frankly, there’s a bit of a lie there.”

Ms. Guadagno remained unruffled, sticking to her campaign’s criticism of Mr. Ciattarelli, claiming his tax overhaul plan amounted to a $600 million tax increase, an allusion to his plan to raise income taxes on those making over $750,000 and $1 million annually. Mr. Ciattarelli says the increase would be offset by other tax changes.

Mr. Ciattarelli’s aggressive posture comes as he finds himself trailing Ms. Guadagno in fund-raising and early polling, though he has recently edged closer. The one-hour debate, held at NJTV’s studio here, was the final time the two would meet on stage in a televised encounter before the June 6 primary.