* 74-22 vote for $109 billion road, rail construction bill
* Speaker Boehner holds out hope for House version
* March 31 construction funding deadline, layoffs loom
WASHINGTON, March 14 (Reuters) - The U.S. Senate on Wednesday passed a two-year $109 billion transportation bill to rebuild roads, bridges and rail systems and sent the measure to the House of Representatives, where deeply divided Republicans left its fate uncertain.
House Speaker John Boehner has said he will take up the Senate bill if Republicans cannot agree on a longer-term measure that reforms public transit funding.
But time is running short, as funding authority for highway and rail construction projects expires on March 31. Some 1.8 million construction workers could face layoffs if no action is taken before then, according to Senate Democrats.
Boehner spokesman Michael Steel said House Republicans still hoped to build support for their own approach.
"If we can't get there, we may have to take up something like the Senate bill - but we'd prefer to take the responsible approach on this and get a longer-term bill through the House," Steel said.
The House transport bill, a five-year $260 billion measure, has faced difficulties from the start, alienating fiscally conservative Republicans over its cost, while Democrats and some Republicans have opposed a provision that would end dedicated funding for mass transit projects. The Senate's bill does not include the mass transit funding changes.
The Senate approved the measure with strong bipartisan support on a 74-22 vote, even after rejecting several attempts by Republicans to load it with provisions ranging from the Keystone XL oil pipeline project to religious waivers from the Obama administration's health insurance policies, including contraception coverage.
Other energy-related amendments failed to gain enough Senate votes for passage, including new tax incentives for natural gas-powered long-haul trucks, expanded U.S. offshore oil drilling and an extension of tax breaks for wind and solar power and advanced biofuels that expire at year end.
White House spokesman Jay Carney urged the House to "move swiftly and in similarly bipartisan fashion" to pass the Senate bill, adding that it would create jobs and make the U.S. economy more competitive through improved infrastructure.
Senator Barbara Boxer, a Democrat who heads the Environment and Public Works Committee, said while the bill contains some reforms and provides some road funding certainty to states, the bill's two-year length was a shortcoming.
"We just didn't have the long-term funding source resolved. That's our next big project," she told reporters.