A bipartisan Senate bill aimed at increasing energy efficiency was rejected late Monday because of a dispute over the Keystone XL oil pipeline and greenhouse emissions.

The measure, co-sponsored by Sens. Jeanne Shaheen, D-N.H., and Rob Portman, R-Ohio, on its surface was not controversial. It called for tighter efficiency guidelines for new federal buildings and tax incentives to make homes and commercial buildings more efficient.

But like many seemingly innocuous legislative endeavors in recent years, the measure — which easily cleared a parliamentary hurdle last week — was caught in the crossfire of a larger political and partisan fight.

Senate Majority Leader Harry Reid, D-Nev., refused to allow GOP amendments, including a measure that would have approved construction of the proposed Keystone XL pipeline that would carry Canadian crude oil from Alberta's tar sands to refineries on the Gulf Coast. The move infuriated Republicans, causing most to oppose the bill.

Republicans also were seeking amendments to speed up natural gas exports, block new Environmental Protection Agency regulations on new coal-fired power plants and ban a tax on carbon emissions.

Reid said he rejected the GOP provisions because they weren't germane to the legislation.

The majority leader offered an up-or-down vote on the bill with a promise for a separate vote on Keystone later. But Republican leaders characterized the deal as a disingenuous political tactic.

The 55-36 vote on the bill fell short of the 60 needed to cut off debate and proceed toward a final vote. Republican Sens. Kelly Ayotte of New Hampshire, Susan Collins of Maine and Portman joined Democrats in supporting the measure. Reid switched his "yes" vote to "no" in a parliamentary maneuver that allows him to revisit the bill at a later date.

Shaheen said the legislation she helped craft fell victim to "election-year politics," but vowed to continue pushing for it.

Reid blamed Republicans for the bill's failure, saying they were holding the measure up for "ransom."

"They’ve held this bill hostage as demand after demand has been met," he said. "Why is this bill at risk? I’ve spoken with some of my Republican colleagues who come to me asking, 'Harry, how can we get the Senate back on track?'"

But Sen. Dan Coats, R-Ind., accused Reid of trying to ram through the measure — which mimicked Obama administration energy policy — while ignoring the concerns of the minority party.

"Over the past 10 months, the majority leader has allowed just nine roll call votes on Republican amendments," Coats said. "It is time to get serious and have a real conversation about energy solutions with bipartisan support, like constructing the Keystone pipeline."

Portman said the measure's failure was "yet another disappointing example of Washington’s dysfunction." But he also criticized Reid for dismissing GOP efforts to amend the bill.

"It’s a sad day in the U.S. Senate when more than 270 organizations — from business to environmental groups — can get behind a good, bipartisan effort, but we can't get votes on a few amendments to pass it," he said.