New Jersey voters would get to decide whether the state should borrow $600 million to preserve open space, farmland, and historic sites over the next three years under an amendment to a bill expected to be introduced today.

State Sen. Bob Smith (D., Middlesex), chairman of the Senate Environment Committee, previously introduced a bill that would authorize the sale of $300 million in bonds.

Yesterday, he said he planned to amend the amount to $200 million for each of the next three years. His committee is scheduled to discuss bill, S1858, today.

"Right now we have the opportunity of a lifetime," Smith said. "Property prices are very reasonable."

He said he wasn't particularly worried that the borrowing might be a tough sell during a recession.

"It might be an easier sell than you think. We'll relay to the average person what this means, and it means very little out of anyone's pockets in a given year. But the benefits" - environmentally and economically - "are so big," Smith said.

Although the original bill had bipartisan support, the larger amount may draw more opposition.

Gov. Corzine, who will seek reelection in November, has said only that he thinks open-space funding will be on the ballot this year. He has not disclosed how much borrowing he would support.

Some environmental advocates would rather dedicate tax revenue to support open space than rely on another short-term funding mechanism.

Jeff Tittel, director of the New Jersey chapter of the Sierra Club, said he worried that a $600 million bond issue would face a tough time at the polls.

"I would only support a bond if there's a way to pay for it," Tittel said. "I'm concerned if there's not a way to pay for it they'll end up cutting" the Department of Environmental Protection's budget.

In 2007, voters approved the sale of $200 million in bonds for open-space preservation, 54 percent to 46 percent, a slimmer majority than in previous open-space questions. Observers believed that was because of voters' concerns about state spending.

The Garden State Preservation Trust allocated the last money from that bond sale March 11.

Smith said he believed voters would see the bigger picture and approve the borrowing.

"I believe that citizens think long-term," he said. "I think they don't just say, 'What's the story today?' but, 'Ten years from now, what kind of state do I want to live in?' I think they will be very supportive of it."

Contact staff writer Adrienne Lu at 609-989-8990 or alu@phillynews.com.