In one of the nation's most ambitious efforts to preserve vanishing farmland and woodlands, the New Jersey Legislature passed a ballot measure Thursday that will ask voters in November to approve borrowing $1 billion to protect half of the state's remaining 2 million acres of undeveloped land over the next 10 years.

The vote was a major triumph for Gov. Christie Whitman, who had made preserving 1 million acres of open space the top priority of her second term. It came just days after members of her own party dealt her a major blow by rejecting her other top priority: an increase of 4 cents a gallon in the gasoline tax, to be phased in over three years, for mass transit and highway projects.Whitman outlined her proposal to preserve open space in her inaugural speech in January to address mounting concern from residents and local officials about the impact of rapid development on the state's landscape and the quality of life in fast-growing towns.

She said she realized that dramatic steps had to be taken because, traveling around the state in her first term, she could see that much of the state's rural character was quickly disappearing because of development pressures.

Municipal officials across New Jersey had embraced development for years, mainly to expand their property tax bases. But now a growing number of local officials are finding that unchecked growth is driving up local property taxes and causing traffic congestion and overcrowded public schools.

"The people see what is happening around them," said Michael Catania, executive director of the Nature Conservancy of New Jersey, a nonprofit organization that has helped protect environmentally sensitive lands from development for more than a decade. "They see what is being lost."

Although New Jersey voters have strongly supported open-space bond referendums in the past, Whitman said that she would campaign aggressively during the next several months to win voter approval for this measure.

The Senate approved the bill unanimously; the General Assembly voted 70-3 in favor, with little debate. Supporters in the Legislature described the resolution as one of the most important initiatives for the state's future.

Last month, Republican leaders rejected Whitman's initial proposal to pay for the preservation of 1 million acres with a gasoline tax increase of 2 cents a gallon. Whitman agreed instead to push for legislative approval of a bond referendum that asked voters to consider the $1 billion borrowing plan.