If you laid all the lobbyists who support it head to toe on K Street, they’d stretch across Washington.

Truckers and railroaders have put aside a bitter rivalry to push for it. Bicyclists and bus companies want it. The Chamber of Commerce and the unions are behind it. So are the asphalt pavers and the safe highways people.

Not a single member of Congress is against it.

So a transportation bill ought to be a quickly done deal, right?

Not so in modern Washington, where the chasm between partisan visions and perspectives never has been so great.

If the two wildly different transportation proposals making their way through the House and Senate were the transcontinental railroad, chances would appear slim that they would meet in the middle. They might not even end up in the same state.

“I believe we will get it done,” said Sen. Barbara Boxer (D-Calif.), a prime mover behind the Senate bill. “Will it be pretty? Of course not. Everybody who says it’s like making sausage, it’s a lot uglier than that.”

There is a lot at stake.

Dwarfed by worries over jobs and overshadowed by bitter social divides, the nation’s transportation network is a mess and getting worse. Though portions of it appear immaculate and a profusion of construction sites give a false sense of security, much of what exists is badly deteriorating, and there isn’t enough of it to support a burgeoning 21st-century America.

The bills in play this week would fund transportation at roughly $53 billion a year. The experts say it would take about $262 billion a year to renew and expand the infrastructure needed to support the economy and growing population. Gas tax revenues have grown too meager to support the system that they built. Congress has been in a dither over what to do about that since the last long-term transportation bill expired more than two years ago.

Now they have reached a crisis point from which there is little chance of escape, experts say.

Unless they address the funding issue, the Highway Trust Fund that the gas tax has supported is projected to run out of money as early as October. If that happens, the spigot that produces some funding for virtually all aspects of surface transportation runs dry.

“If the pieces don’t come together now, it’s a very shaky situation moving forward,” said a senior Senate staff member who is not authorized to speak publicly. “The money’s going to run out. If they cut transportation to the levels that are currently in the trust fund, we would lose 630,000 jobs and it would devastate the economy.”

Disparate bills

Those pieces, in many respects, appear radically different.

Painted with broad brush strokes, the House Republicans want to reform and streamline the transportation system and refocus priorities on a core mission to maintain and expand the highway system the trust fund was established to build.

Democrats and many of their Republican allies in the Senate like the notion of cutting red tape that slows construction projects, but they embrace a more traditional approach that supports a triad of transportation options.

The Democrats would like a longer-term bill, but they’ve settled on two years while they work out the funding challenge. The House Republicans insist that the money is there for a five-year bill and say that state planners need the assurance of longer-term funding.

It’s in the weeds that the two bills differ most, and that’s where the controversy bubbles up.

The House bill would cut off transit systems from a share of the highway trust fund, a pipeline that has sent 2.86 cents of the 18.4-cent federal tax on a gallon of gasoline their way. Instead it would raise about $40 billion by requiring federal employees to pay 1.5 percent more into their pension fund. The second big new source of revenue in the House bill is expansion of offshore oil drilling, a funding stream that would take several years to develop.

The House bill also has raised the ire of cyclists and pedestrians by eliminating a program that required states to use a small portion of federal money for bike paths and sidewalks.

The Senate bill includes dedicated transit system funding and provides money for bikes and walkways but lets states use it for other things if need be. It augments what’s left of the trust fund by tapping several sources that few people ever heard of: $3 billion to $4 billion of it comes from an underused fund to deal with underground storage leaks and another pot of money appears from something known as black liquor, a byproduct of paper-making that can be burned as fuel.

After the House bill stirred up controversy, the Republicans on Tuesday divided the package into three parts, one dealing with transportation, the second with offshore drilling and the third with federal pensions. House Speaker John Boehner’s statement that the split would allow greater transparency drew snickers from cynics who said the bill was too laden with controversy to pass as a whole.

The Obama administration already is threatening a veto if the House bill gets to the White House. Transportation Secretary Ray LaHood, a former Republican member of the House transportation committee, has denounced it as “the most partisan transportation bill that I have ever seen.”

“The Democrats are not going to sign on to the radical surgery that’s coming out of the House,” said a former senior transportation official who served in the administrations of both Bush presidents. “I just can’t imagine that. It’s fundamentally an anathema to them and to a lot of other people as well.”

Running out of time

Boxer and a wildly diverse coalition of transportation advocates are less worried about what the House passes than they are that the House won’t approve a bill at all.

“Anything that gets this into the conference committee I strongly support,” Boxer said, “whether it’s in three pieces or one piece, doesn’t matter to me. This has been done many times and we’ll figure it out. We need to get to conference and get this done before March 31. ”

That’s when the latest extension of the transportation bill signed into law in 2005 will expire.

After a messy fight over a funding extension bill last summer led to a partial shutdown of the Federal Aviation Administration, the extension option is one Boxer wants to avoid.

“Time is of the essence,” said Janet F. Kavinoky of the U.S. Chamber of Commerce. “If they don’t get these two bills out quickly and start making substantial progress on a conference, we’re going to have an awfully hard time getting a product to the president in time to get a bill in place.”

With unemployment among construction workers running at about twice the national average, there is another urgency to consider.

“The other deadline is that we could lose another construction season to uncertainty without passing the multi-year bills,” said Jeff Schoaf of the Associated General Contractors of America.

Dave Bauer of the American Road and Transportation Builders Association said construction companies are in limbo while they wait for Congress to act.

“They’re not going to go out and hire people they’re not going to be able to keep on the payroll two months from now,” Bauer said. “This game doesn’t go forward unless both chambers move. The can has been kicked around for a very long time. We don’t want to see this moment slip away.”