With two of five members opposed, a multistate agency that has spent years developing regulations for natural gas drilling in the Delaware River watershed has canceled a key vote scheduled for Monday.

The Delaware River Basin Commission announced Friday it was postponing a vote on hydraulic fracturing, or fracking, to give the agency's five commissioners more time to review the draft regulations. No new meeting date has been set.

The rules need three votes to pass, though the commission had hoped for unanimous, bipartisan support. Delaware Gov. Jack Markell, a Democrat, told the commission Thursday he would not support the regulations because of concerns over drinking water protections. Earlier, New York, whose governor also is a Democrat, had announced it would vote no. Republican-led New Jersey and Pennsylvania had not announced how they would vote, but it was believed both would vote yes. It's not known how the fifth member, the federal Army Corps of Engineers, was planning to vote.

Pennsylvania Gov. Tom Corbett said he was disappointed by the latest delay, which he said happened because commission members disagreed on the regulation package. Environmentalists claimed victory, saying the commission lacked the votes to proceed.

"Pennsylvania is ready to move forward now," Corbett said Friday. "We have demonstrated a willingness to compromise and to address issues brought forth by other members of the commission. We have worked with our commission partners in good faith, and it is disappointing to not have these efforts reciprocated."

Fracking involves injecting water, sand and chemicals into a gas well to crack surrounding shale thousands of feet underground so trapped natural gas can flow into the well. Environmentalists fear it could result in contamination of drinking water supplies.

Because of that fear, New York regulators are proposing to ban fracking in the New York City and Syracuse watersheds. New York state has had a moratorium on fracking since regulators started an extensive environmental review in 2008. The state is now holding hearings on proposed regulations, which, if approved, could allow drilling next year.

The commission manages water use for the Delaware River Basin, and environmentalists say the drilling would threaten drinking water for 15 million people.

The proposed rules would allow 300 natural gas wells in the Delaware River Basin, followed by a commission review before more are phased in. The eventual total could reach many thousands of wells.

The New Jersey Sierra Club reported that there are 10,000 leases on hold in the basin that could move forward if the regulations are adopted. The National Park Service estimates 35,000 wells eventually could be constructed.

Pennsylvania already allows drilling outside the watershed area. New Jersey has no Marcellus shale, so its interest in the issue revolves around water quality.

The federal Environmental Protection Agency is studying the effects of fracking, with a draft report due next year. Environmental groups have gathered more than 73,000 signatures on a petition opposing drilling in the watershed.

(Copyright 2011 by The Associated Press.  All Rights Reserved.)