TRENTON - Lawmakers never like to target their own.

And New Jersey's ping-pong game over a ban on holding two elected offices is no different.

The state is home to the most double-dippers in the country - and its leaders say stopping it is a priority.

But bogged down in politics, the ban stalled again this week in a disagreement between the two legislative chambers - and that was even after a consensus to protect the 19 lawmakers who also hold local offices.

The thorny question became when the ban would take effect - and the answer could influence several North Jersey races in the fall.

"It's troubling that this kind of a disagreement with political overtones could be stopping progress in New Jersey on such an important ethical issue," said Jon Shure, president of the liberal think-tank New Jersey Policy Perspective.

"But the issue is important enough, and there is enough momentum, that they will resolve this," Shure predicted.

Yesterday, Gov. Corzine said he was still asking for the ban, and state Senate President Richard J. Codey pledged that one would be enacted by year's end.

"It may take longer than . . . I would like to see," Codey said, "but we'll get it done."

Holding two elected offices is illegal in 11 states. But for years it has been an accepted practice in New Jersey, which has a part-time legislature.

Recently, however, the practice has come under scrutiny. Last year, New Jersey Policy Perspective released a study finding that dual-office holders were stretched too thin and prone to conflicts of interest.

For example, legislators can direct state grants to townships they lead. The study pointed out that in 2005, $2 million in special grants went to West New York in Hudson County, where the mayor was also Assembly Speaker Albio Sires, and $225,000 went for an ambulance and vans in Union City, whose mayor is Democratic Assemblyman Brian Stack.

The study found 19 other officials simultaneously holding municipal and county offices.

Last year when lawmakers recommended ways to reduce property taxes and cut government costs, banning dual-office holding was one.

But the proposal had to get past a legislature filled with dual-office holders - and political resistance threatened to kill it. The Senate yanked it out of a public employee benefits reform bill before passing it.

But then Corzine demanded the ban.

The Assembly put it back into the pensions bill, and most of the house's dual-office holders - including Paulsboro Mayor John Burzichelli and Washington Township Mayor Paul Moriarty - voted in favor.

The Assembly language would not only have let current dual-office holders keep serving continuous office, it would also grandfather anyone who takes a second office until Feb. 1, 2008.

This would protect Stack - who wants to leave his Assembly seat and run for Senate.

But that change didn't make it past the Senate, where leaders decided they wanted a ban that would take effect immediately.

Critics grumbled that was no surprise. After all, they said, Senate Democrats have no incentive to help Stack secure a seat now held by their own majority leader, Bernard Kenny.

On Monday night, the Senate gave preliminary approval to an immediate ban - sponsored by Democratic Sen. Sharpe James, who was also mayor of Newark until last year.

"I never wanted to be a dual-office holder," James said. And if he had resigned as mayor, "that doesn't solve the problem. I've solved the problem now" by sponsoring the bill.

Though an earlier version of his bill contained the 2008 date, James said Monday that if the ban was not immediate, "you're playing politics. . . . I don't think you should target the bill for any particular individuals."

He avoided questions as to whether one of his motivations might be his own Senate seat. James may face a challenge in the fall from a Newark councilman. And an ally, Ronald Rice (D., Essex), might be challenged by a county freeholder.

The Senate's action infuriated Assembly leaders, who said this would kill the whole issue because an immediate ban would not clear their house.

"This was a last-minute change that created an enormous problem," said Assembly Speaker Joseph Roberts (D., Camden). "I have a lot of members who think the change was more about incumbency protection than about dual-office holding."

Assemblyman Reed Gusciora (D., Mercer) said that if the Senate really wanted to strengthen the ban, it should apply it to all current dual-office holders.

In fact, Sen. Tom Kean Jr. (R., Union) tried to advance such legislation on Monday, but Democrats killed it. Kean said, "I don't see how it makes any sense to say it's wrong for one group of people and OK for another group of people."

Democratic Sen. Stephen Sweeney, who is also Gloucester County's freeholder director, said he thought the ban was "silly" but voted for it anyway because Corzine had demanded it.

Sweeney said voters decide who takes office, and a ban wouldn't save any tax money.

But Shure, the think-tank president, said the goal of the ban wasn't to save money. It was to send a message that "this is a government that is more worth funding, because it is operating in a more up-and-up way."

Contact staff writer Elisa Ung at 609-989-9016 or eung@phillynews.com.