The Senate is taking up a series of more than 20 amendments today, which, once complete, will clear the way for passage this evening or tomorrow of a $109 billion measure that would authorize the nation’s surface transportation programs for two years.

The Senate voted on the first two amendments before recessing for the weekly party policy lunches, defeating the first amendment and approving the second.

A proposal from Sen. Jeff Bingaman (D-N.M.) was adopted 50-47 and would prevent privatized highways from being taken into account when doling out federal highway funds.

“Under existing law, privatized roads are still included in the calculation of how much a state receives in federal highway funds,” Bingaman said before the vote. “It does not make good sense for a state to be credited with federal funding needed to maintain that road once it has been shifted out of the public sphere to a private entity.”

The Senate rejected an amendment from Sen. Jim DeMint (R-S.C.) that would have scrapped the current federal transportation funding program. The amendment was defeated 30-67.

Currently, states collect a federal gas tax and send it to the federal government; it is then distributed back to states according to a formula.

DeMint argued that most states pay more into the system than they get back and he said scrapping the current funding system would empower states to have more control over the transportation decision within their borders.

“The problem is that … the majority of states get back less than we spend,” DeMint said.

“The current … transportation finance system is broken,” he continued, adding that the program spends more than the amount of gas taxes it brings in.

DeMint also said his amendment would allow states save money because they would no longer be required to comply with the Davis-Bacon Act, a depression era law that requires that workers be paid prevailing wages on federally-funded projects. Republicans typically oppose Davis-Bacon because they say it raises the cost of projects.

“My amendment would free states from the wasteful and corrupt Davis-Bacon Act, which needlessly forces the government to pay labor union wages for construction projects,” DeMint said. “Davis-Bacon harms workers who choose not join unions and it raises the cost to taxpayers.”

DeMint said the act increased the cost of federally funding projects by $11 billion last year.

Sen. Barbara Boxer (D-Calif.), chairman of the Environment and Public Works Committee, urged that the amendment be defeated. “This is the end of the federal highway transportation system,” Boxer said. “This is a disaster if it were to pass.”

The Senate is expected to resume voting this afternoon on up to 20 more amendments, including a proposal from Sen. Pat Roberts (R-Kan.) that would approve the 1,700-mile Keystone XL oil pipeline and extend certain energy-related tax breaks that expire at the end of the year.

Other amendments on the docket include a proposal from DeMint to repeal a raft of energy-industry tax breaks and a plan to reduce the corporate tax rate.