Last week, Sen. Barbara Boxer unveiled her Senate Environment & Public Works Committee’s plans for surface transportation legislation. If it holds up, the plan would preserve funding and authorize it for six years, giving state and local leaders the stability they need to perform long-term projects. Unfortunately for them, there’s almost no chance her proposal will become law in the near future.

Though the actual text of the bill hasn't been completed -- that should happen in a few weeks -- Boxer revealed a broad set of parameters that will be included in the legislation, which allocates $339.2 billion over six years for surface transportation. That's the value of  SAFETEA-LU, the previous six-year bill, adjusted for inflation. Markup of the bill is expected to be complete by the July 4 recess.

But the transportation community has greeted her plan with a mixture of silence and skepticism. For starters, it’s unlikely that the House transportation committee, led by Rep. John Mica, would be able to draft a bill that resembles Boxer's proposal.

Mica’s committee is stacked with freshmen who have little allegiance to a transportation program, and he faces a Republican leadership focused on budget cuts. The Republican-controlled House Appropriations Committee, for example, announced last month that in FY 2012, spending for Transportation and Housing and Urban Development will be capped at $47.7 billion -- a 30 percent drop compared to 2010. Even if every dollar of that total went into the surface transportation bill, it would come up short of the annual total proposed by Boxer.

The House committee hopes to release its version of the bill within the next few weeks, committee spokesman Justin Harclerode tells Governing.

Meanwhile, it’s unclear how Congress would fund Boxer’s plan. “This is an authorization bill,” Boxer told reporter last week. “The Finance Committee has the responsibility of finding the pay-fors.” As a six year-bill, her proposal comes up short $12 billion annually, and as a two-year bill, it comes up short $6 billion annually. That’s due to the challenges facing the Highway Trust Fund – largely funded via fuel taxes – which is the primary way the highway bill is funded.

Boxer's comments are similar to those of Transportation Secretary Ray LaHood who, in an interview with Governing earlier this spring defended the president’s proposal for an even larger six-year, $556 billion surface transportation by saying Congress could figure out the details.

Additionally, many in the transportation committee think it's rapidly becoming clear Congress won't pass a six-year bill. Among those skeptics is Sen. Jim Inhofe, the Republican ranking member on Boxer's committee.

That would be frustrating to state and local transportation officials, who say it's critical for them to have a long-term allocation since a short-term bill would make planning larger projects a challenge.

But given the fiscal realities, a short-term bill may actually be more likely to pass Congress, and it could be beneficial to states if it would mean larger yearly allocations in the future. Boxer herself acknowledged a two-year bill is a possibility. “We’re hoping for a six-year, but we recognize that the funding challenges may be so that we decide to go with a two-year,” Boxer said.

Sean Slone, transportation policy analyst for the Council of State Governments, says a short-term bill would allow Congress to “kick the can down the road” in hopes that it could have better luck crafting legislation in a few years. But he’s skeptical of that technique, since it’s unlikely that in just a few years federal lawmakers would suddenly find it easier to raise the gas tax or switch to a vehicle-miles traveled fee – two steps considered by transportation experts as integral to preserving Highway Trust Fund revenue and transportation spending but opposed by the administration.

Many of the voices who are usually vocal about transportation legislation – including the American Association of State Highway and Transportation Officials, and the American Road & Transportation Builders Association -- were surprisingly quiet in the wake of Boxer's comments. Both declined to comment to Governing on the merits of her specific proposals, saying only that that they were pleased the process is moving forward. That may be because Boxer's plan hasn't been put into a formal bill yet. It also may be due to skepticism.

Joshua Schank, president and CEO of the Eno Transportation Foundation, says that the dollar amount offered by Boxer isn't impossible, but it's likely "at the top of what could be achieved." And the $339.2 billion in her proposal is vastly more than what will be offered up by Mica's committee. Given that gap, the Mica and Boxer bills probably won't be reconciled any time soon, making passage of a long-term bill unlikely this year, Schank says.

The highway bill is operating under a sort of informal timeline. Some transportation experts speculate that if a bill isn't passed by Congress by the fall, it won't happen until 2013, since the upcoming 2012 presidential campaign could create an environment that is too politically charged for the legislation to survive.

Schank suggested one alternative that may actually be surprisingly attractive for states: yet another temporary spending bill. If the Boxer and Mica bills can't be reconciled before the current stopgap highway funding bill expires later this year, then Congress could simply pass another temporary bill. And if that legislation provided level funding, it might be better for states than any long-term bill Congress could pass. Meanwhile, the Boxer and Mica proposals would serve as a foundation for legislation the new Congress could take up in 2013.

Boxer's plan did have a major victory for cities and states: an expansion of TIFIA, which allows state and local governments to borrow federal funds so that they can accelerate their own transportation projects. TIFIA's funding level increased from $122 million to $1 billion annually, and it can now be used to fund 49 percent of project costs instead of 33 percent.

Los Angeles Mayor Antonio Villaraigosa had been among biggest cheerleaders for the plan. He also stands to benefit, as he hopes to use TIFIA funds for a major transit expansion.

Boxer said it should also appeal to rural communities, since a component of the leveraging plan gives especially favorable rates to rural areas.