The emergent high speed rail lobby, which we highlighted in a story today as part of our Transportation Lobby project, may be approaching its first true challenge. Organizations like the U.S. High Speed Rail Association, reform coalition Transportation for America, the U.S. Public Interest Research Group, French conglomerate Alstom, and other regional advocates recently joined advocacy efforts and created a website at fourbillion.com to pressure the Senate into matching the House’s proposed $4 billion appropriation for high-speed rail in next year’s budget.

The House’s 2010 appropriations bill still needs to be reconciled with its Senate counterpart, which was passed this summer with $1.2 billion designated for high speed rail. The White House requested just $1 billion, leading senators to argue that they have already overspent expectations.

But the disparity continues to be a hang-up, with rail advocates and industry reps eager to seize on as much momentum as possible — and push for the higher figure. Whatever emerges will be on top of the $8 billion already targeted for high speed rail in the American Recovery and Reinvestment Act.

“Eight billion dollars in the stimulus is not going to go very far,” said Texas Democratic congresswoman Eddie Bernice Johnson at last month’s U.S. High Speed Rail Conference. “We know that.”

But Johnson’s Senate colleagues may feel they have no choice but push back against the House’s higher spending total. After all, Washington is already getting an earful from other interest groups that are part of the wider transportation lobby. They all want their own piece of the pie, and they’re agitated over ongoing delays in a larger proposed transportation bill that could steer policy for six years and be worth $500 billion. There’s also the increasing alarm over federal deficits. Suddenly, everyone appears strapped for cash.

“You can imagine that some of the other modes [like highways and light rail] are a little bit jealous of the attention that high speed rail is getting right now,” says Rod Diridon, who leads the high speed rail committee at the American Public Transportation Association, a group that already has its own troubles trying to fund mass transit systems.

Just to keep current transportation programs afloat, twice in the last 15 months Congress had to take multi-billion dollars amounts from the general treasury. Eight billion dollars in September 2008 and another $7 billion this past July went to bail out the highway trust fund, which pays for road and mass transit projects throughout the country. That fund will continue to flirt with bankruptcy barring a gas tax increase or new sources of revenue. The crisis has handcuffed House Transportation Chairman James Oberstar in his quest to pass that giant, multiyear transportation bill — a bill that includes $50 billion for high speed rail.

“My major concern is we’re starting to replicate the old way of doing business,” says Stephen Van Beek of the Eno Transportation Foundation, a nonprofit transportation research group. Van Beek cautions that rushing headfirst into high speed rail before tackling the nation’s entire transportation vision as a whole could worsen what one Congressionally appointed commission described as a patchwork, politicized federal process.

“But I certainly don’t blame any parochial interest for being excited,” says Van Beek, “because if you look across transportation right now, nobody has any money.”

The mass transit association, for one, endorsed chairman Oberstar’s proposed $50 billion for high-speed rail after much internal discussion, in part because the funding would come from a separate source outside the trust fund, such as a newly formed National Infrastructure Bank. But if the money instead comes into conflict with traditional interests, some insiders argue it might cause other transport groups to grow more than a little jealous.

“I think the highway interests and some of the transit interests are gearing up,” says one long-time lobbyist.

“And Congress knows that if they [spend $4 billion on high speed rail], this is not a one-time thing.”