TRENTON -- A 2 percent cap on the raises police and fire unions can win in arbitration saved property taxpayers nearly $3 billion and should be renewed before it expires in December, according to a report released Thursday by rogue members of a state task force.

Proponents credit the 7-year-old cap with slowing the growth of New Jersey's sky-high property taxes and warn that taxpayers will take a hit through increased taxes or reduced services if it is permitted to sunset at year's end.

While Republican lawmakers have urged the cap be extended indefinitely, Democrats -- including gubernatorial nominee Phil Murphy -- have said they were awaiting the task force's recommendations.

But earlier this week, the panel deadlocked 4-4 on releasing the report. Four of the eight voting members were appointed by Gov. Chris Christie and four members from public labor were appointed by Democratic leaders of the state Legislature.

Despite the vote, the administration-backed members jointly released the report Thursday morning.

"The wait is over," said state Assemblyman Declan O'Scanlon, R-Monmouth, appointed by Christie to serve on the task force. "It is time to weigh in. Do they stand with the taxpayers? Or are they going to torture a way out of taking a position?"

Ed Donnelly, president of the New Jersey Firefighters Mutual Benevolent Association and a member of the task force, said the governor's appointees released a one-sided analysis over half the panel's objections.

"It's not that we didn't want to release the report," he said. "We want to release a comprehensive report with all the recommendations reflective of both sides of the board. You don't have that today."

Donnelly said the report ignores other factors that may be influencing property taxes, such as pension and health care reforms. The task force also split 4-4 on the union members' request to seek additional information.

"You've got half of the committee not signed on to this. So as far as I'm concerned, it's a sham," he said. "We're going to tell the Legislature to throw this thing in the garbage and request the task force to get back to work."

A spokesman for Murphy, Derek Roseman, called the the rogue release "a transparent political stunt," that the gubernatorial front-runner won't legitimize.

State lawmakers installed the cap in 2010 to help local government officials stay within a state-mandated 2 percent cap on annual increases in spending.

"Without these reforms, public employers were placed in the untenable position of having to limit their budgets to the 2 percent tax levy cap, while at the same time having little control over one of the largest line items in their budget -- police and fire salaries," the report said.

The report says it's working to slow increases in police and fire salaries and property taxes.

Taxpayers paid $2.9 billion less from 2010 to 2015 than they would have been charged if property tax bills continued to increase at the pace prior to both caps, it found, estimating $530 million in savings from police and firefighter salaries.

"Total property taxes would have risen an average of 4 percent per year instead of 2 percent through 2015," it said. "The direct and immediate impact of these legislative initiatives is remarkable."

Employers and unions head to arbitration when they can't agree on contract terms. The vast majority of contracts are settled through voluntary negotiations.

While there were 121 interest arbitration cases filed in 2010, last year there were just nine, according to the report.

The report found that the award cap has had "a profound effect on limiting interest arbitration to a procedure of last resort, leaving it to the parties to settle labor contracts through direct negotiations and within budgetary constraints."

The average arbitration award since 2010 has been limited to 1.85 percent, it said.

Data from the Public Employment Relations Commission shows that average awards ran as high as nearly six percent in the decades before the cap, but were falling before the cap took effect.

While the cap applies only to salary increases awarded through arbitration, proponents claim it set the tone for negotiated settlements between public employers and public safety unions. But the task force said it couldn't "conclusively" assess the impact of the cap on these more common voluntary settlements reached at the bargaining table.

In addition to examining whether the cap is working to control property taxes, the task force studied whether it harmed response times or local department's ability to hire and retain workers.

The report says it found no evidence the cap triggered increased crime rates or damaged recruiting for police and firefighters, noting that the number of prospective police officers and firefighters is climbing.

The cap law also reined in the often lengthy waits for arbitrators to resolve disputes to 90 days.

O'Scanlon said the analysis overwhelmingly proves the cap's success and refutes any argument against it.

"There is nobody that is arguing that this policy ought to sunset except labor leaders," he said. "Certainly, the data is overwhelming. In fact, there's no data to the contrary."

The study's findings leave no question the law should be extended, he added.

Christie said he would sign a bill re-upping it during the lame-duck session if the Legislative moves one.

The law was extended and tweaked a first time in 2014 without a single vote against it.

Shortly after the report's release Thursday morning, Christie released a statement, saying "these findings prove the arbitration cap works."

"Before this cap sunsets at the end of this year, New Jersey's leaders in control of the legislature must make this a permanent reform," Christie said

Samantha Marcus may be reached at smarcus@njadvancemedia.com. Follow her on Twitter @samanthamarcus. Find NJ.com Politics on Facebook.