WASHINGTON -- The Senate narrowly approved a measure Thursday requiring the Army to wait a year before deciding whether to push ahead with a controversial expansion of its Pinon Canyon Maneuver Site in southeast Colorado.

The bill's sponsor, Democrat Ken Salazar, said the measure would provide a "cooling-off period" in the heated debate over the issue. But Senator Wayne Allard, a Colorado Republican, voted against it, saying it was too restrictive.

The House has passed an identical measure. Both bills will go to a conference committee to work out other differences.

President George W. Bush is expected to sign the completed bill.

Representative Doug Lamborn said he supports the Army’s plans for expanding the base and was disappointed with the Senate vote.

“I would like to see the Army given the opportunity to go forward with the study as soon as possible,” said Lamborn in a statement. “I believe inhibiting the Army’s ability to engage in constructive dialogue with the surrounding community, will exacerbate, rather than alleviate, the tensions related to the issue.”

The Army says it needs to increase the 368-square-mile Pinon Canyon site to about 1,000 square miles to accommodate the arrival of 10,000 more troops being transferred to Fort Carson. It has said it would be too expensive to ship the soldiers elsewhere for training.

Supporters of the expansion fear that blocking it could make Fort Carson vulnerable to closure.

But ranchers near the site say the expansion would take too much land out of agricultural production, damaging the economy. They and other property owners also fear the Army will force them to sell their land, despite assurances from the military that it hopes to get the acreage from willing sellers

Salazar said delaying a decision on the expansion is a compromise. He had been in a political bind for months over the issue, under pressure from groups on both sides.

"There are legitimate questions that have been raised about the expansion. There are key issues related to property rights, relating to fiscal discipline ... and key questions relating to the ranching economy and the heritage of southeastern Colorado," he said.

Lamborn disagreed and said, “Congress would still have to appropriate the funds for the Army to purchase any land and it should be at that point, not before, that those opposed to the plan seek a legislative solution to stop it.”

The Senate passed the amendment on a 47-45 vote. Two Kansas Republicans joined Democrats in supporting the measure.

Allard said the narrow margin shows that senators are hesitant to interfere in the expansion.

"The closeness of today's vote represents the concern many members of the Senate feel regarding the precedent set by this measure," he said in a statement.

Allard said the measure is so restrictive that the Army couldn't even provide informational handouts to the public, hold community meetings to find common ground or conduct a needed environmental study.

"I believe this amendment will unnecessarily tie the hands of the Army and actually prevents the Army from collecting important information," he said.

Allard said he and Salazar agree that the Army must justify the need for the expansion. They plan an amendment to another defense bill requiring the Army to study whether the additional land is needed.

"Where we differed today is on how we should approach this issue," Allard said.