For three days after House Republicans presented a plan for transportation funding, the bill weathered a hail of criticism, including charges that it would gut the funding guarantees on which mass transit has relied for 30 years.

The sweeping reforms in the five-year, $260 billion bill touched nerves on both sides of the aisle and with scores of interest groups that have a dog in the fight. Whether it “hollows out the guts of . . . transportation efforts,” as U.S. Transportation Secretary Ray LaHood told Politico, or is a long-needed refocusing of transportation priorities, as most Republicans contend, the plan was debated hotly in three committees last week.

By the time the last gavel fell, more than a hundred efforts to amend the bill had been beaten back. That exercise will be replayed when the bill reaches the House floor, very likely with the same result. The vast differences between it and a Senate bill caused some to doubt the two could be reconciled this year.

One of the most contentious issues played out in the House Ways and Means Committee on Friday. Since the Reagan administration, 20 percent of revenue that flows into the Highway Trust Fund from federal gas taxes has been earmarked for mass transit. Under current law, 2.86 cents of the 18.2 cent-per-gallon tax goes to transit.

Under the GOP plan, that trust fund money would be redirected to pay for roads and bridges. Mass transit would turn, instead, to a one-time $40 billion allocation from the general fund that would be shared with other popular programs, including bicycle and pedestrian improvements.

After that general fund money runs out, mass transit funding would come through an annual appropriation rather than through the five-year spending umbrella of the House proposal. Where that $40 billion will come from was promised to be revealed this week.

In Friday’s committee debate, it was apparent that Republicans were confident that the general fund would provide reliable funding for mass transit. Democrats and mass transit advocates were apoplectic.

“This is the new version of President Ford saying to New York, ‘Drop dead,’ ” said Rep. Joseph Crowley (D-N.Y.).

Democrats said they doubted that the $40 billion was guaranteed and contended that mass transit ought not have to compete with other programs for it.

“I think we have to be very, very careful about what this can do in destabilizing major [mass transit] projects,” said Rep. Earl Blumenauer (D-Ore.).

Blumenauer argued that transit officials can’t make long-term plans unless they’re confident of long-term funding. His amendment to restore dedicated mass transit funding was defeated in a committee vote.

Committee Chairman Dave Camp (R-Mich.) countered with a Congressional Budget Office estimate that the Highway Trust Fund will run out of money for highway projects in 2013 and for mass transit projects a year later.

“The bill before us today will provide stable funding for these projects for at least the next five years — without raising a dollar in new or higher taxes or adding a penny to the deficit,” Camp said.

The proposal to devote all of the gas-tax revenue to repair of roads and bridges comes from an awareness that major interstates are reaching the end of their natural life span. A panel of experts in 2010 estimated that the nation should spend $262 billion a year to rebuild roads, bridges, water lines, sewage systems and dams, a sum greater than the total that the House proposes to spend over five years.

In an interview afterward, Blumenauer elaborated on his concerns.

“They’re taking a flier. There’s no source that has been identified for the $40 billion,” he said. “Why all the transportation people were apoplectic about this is that it’s a lot easier for people on the Appropriations Committee to take this money and use it for some other purpose if it’s not tied to a dedicated trust fund. At the core, it’s very simple: They take all of the transit money, about 20 percent of the trust fund, shove it into roads, put transit off on its own with a smaller pool that may or may not materialize, and give them more competition for it.”