WESTAMPTON Dozens of interest groups lobbied legislators Wednesday at a Senate budget hearing in Burlington County to maintain or increase funding for their favorite programs next fiscal year, even as New Jersey makes a record payment toward its pension fund.

Among the most pressing issues addressed was the scheduled April 1 expiration of New Jersey's interest-arbitration cap, which sets a 2 percent limit on annual raises for police and firefighters.

Gov. Christie and other supporters of the cap say it has helped slow property-tax growth. Assemblyman Declan O'Scanlon Jr. (R., Monmouth) said he would introduce legislation Thursday that would make the cap permanent.

"Unless the Legislature acts to extend the April 1 sunset, our taxpayers will lose essential protections," Stone Harbor Mayor Suzanne Walters, who is also president of the New Jersey League of Municipalities, told the Senate Budget and Appropriations Committee on Wednesday at the Burlington County Institute of Technology.

The arbitration law took effect in 2011. For contracts completed between that time and September 2013, average raises were 1.86 percent, the lowest in 20 years, according to O'Scanlon, a member of a task force that studied the impact of the law.

The Senate and Assembly budget committees are holding a series of public hearings throughout the state as they prepare to take up Christie's proposed fiscal 2015 budget. The state constitution requires the Legislature to pass a balanced budget by July 1.

Christie's $34.4 billion budget calls for a record $2.25 billion payment to the pension system. The governor says 94 percent of new spending in his budget is allocated toward pension, health benefits, and debt-service costs.

Other interest groups attending Wednesday's hearing included retailers who supported Christie's proposal to require out-of-state online retailers to collect sales tax. The budget includes $28 million in new revenue from closing the loophole.

Brick-and-mortar retailers already required to collect the state's 7 percent sales tax suffer a competitive disadvantage to online retailers, said John Holub, president of the New Jersey Retail Merchants Association.

Christie first announced his support for the controversial tax in 2012, when online retail giant Amazon said it would build two distribution centers in the state, bring 1,500 jobs, and start collecting sales tax from New Jersey residents in July 2013.

That has placed Christie, a potential contender for the GOP presidential nomination in 2016, at odds with other prominent Republicans, who consider the measure a new tax. Christie, by contrast, describes the issue as a matter of tax fairness.

A 2011 Rutgers University study projected that enforcement of the tax would generate about $310 million in revenue for New Jersey in 2015.

At the federal level, the Democratic-controlled Senate passed the Marketplace Fairness Act in 2013. The Republican-controlled House hasn't taken up the bill. In December, the U.S. Supreme Court declined to hear a challenge to a New York law that enforces the tax, clearing the way for other states to follow suit.

"This is not a new tax. It's not an increase in tax. A sale is a sale," Holub told the budget panel Wednesday. "We're simply asking for a level playing field."

State Sen. Samuel Thompson (R., Middlesex), a budget committee member, supported the idea. "It's only right that everybody pays the same amount for the same goods," he said.

A number of groups also pressed the committee to increase funding for providers who help those with intellectual or developmental disabilities, though advocates broadly praised Christie's budget.

"I'm living proof that people with disabilities can work, live, and do great things in their communities," said Colleen Watkins, of the Arc of New Jersey, which advocates for people with disabilities.

Many providers earn a starting salary of about $8 to $9 an hour and have not had a raise in seven years, testified Daniel Keating, executive director of the Alliance for the Betterment of Citizens with Disabilities.

Legislators were sympathetic to such causes, but emphasized that they faced tight fiscal constraints.