Remember Alaska's "bridge to nowhere"? It's about to be topped by what critics call Mississippi's "railroad to nowhere," which is quickly becoming the poster child for excessive spending by the Republican-controlled Congress.

The project, which was added to a $106.5 billion emergency defense spending bill in the Senate, would relocate a Gulf Coast rail line inland, to higher ground. Never mind that the hurricane-battered line was just repaired at a cost of at least $250 million. Or that at $700 million, the project championed by Mississippi's two US senators is being called the largest "earmark" ever.

The controversy points to a deepening split in the GOP over whether to rein in spending in the face of wartime commitments and record deficits - and whether failing to do so threatens their majority in this fall's midterm elections.

Its sponsors say the motive is evacuation and safety. "Along the Coast, we too often seen motorists and pedestrians killed on the rails that have run parallel to our shores for more than a century," wrote Sen. Trent Lott (R) of Mississippi in the Sun Herald newspaper Monday. Mississippi's senior senator, Thad Cochran, chairs the powerful Appropriations Committee, which drafted the bill.

But critics say it's also a bid to open land for developers to turn Mississippi's struggling Gulf Coast into Las Vegas South - and that emergency federal spending shouldn't pay for it, especially when Washington is on track to spend $371 billion into the red.

"There's never been a single earmark anywhere near $700 million," says Ronald Utt, a senior fellow at the Heritage Foundation, a conservative think tank in Washington. Tuesday he released a report, "Deadly Sin: Larding up Emergency Appropriations," which details the CSX freight line relocation plan. "That's more than twice the size of the [$223 million] bridge to nowhere."

Earmarks, or projects that are attached to spending bills without committee or budgetary review, are under intense scrutiny, especially in light of the ongoing corruption scandals on Capitol Hill. If Republicans don't get a handle on corruption and overspending, they could get burned in fall elections, analysts say.

That prospect riles fiscal conservatives, who are urging Republicans to repent before they lose the majority they fought so long to win. Especially critical of the railway earmark is Sen. Tom Coburn (R) of Oklahoma, who is emerging as a fierce opponent of pork projects.

"Emergency supplemental bills are designed to help our nation confront emergencies. While the current location of this rail line may be displeasing to local economic developers and politicians, it is hardly a national emergency," he said in a statement on April 7. He wants Congress to end the practice of earmarks, which he calls "the gateway drug to overspending."

The railway station at Gulfport, Miss., was also a must-stop in the first leg of the Ending Earmarks Express, a project of the free-market Americans for Prosperity Foundation, which is lobbying Congress to curb spending. "We were surprised to see that the area is still very devastated," says spokesman Ed Frank. "It is clearly still an emergency there. But we found it curious that one of the few things that had been completely rebuilt - the railroad - is the thing they want to rip up."

"Our members are getting more and more frustrated that Congress is not exercising fiscal discipline and spending restraint," he adds. "Republicans should be taking this very seriously."

Fiscal watchdog groups say the public is taking notice.

"These 'nowhere' things are starting to gather some cachet in that they are drawing the public's attention to the problem of pork," says Tom Schatz, president of Citizens Against Government Waste. He reported that pork projects in Congress amounted to $29 billion in FY 2006, up from $27.3 billion the previous year.

But local backers insist that the proposed project is hardly a train to nowhere. Unlike the much-maligned Alaska "bridge to nowhere," which linked the town of Ketchikan (population 7,900) with its airport on the island of Gravina, the CSX rail line carries freight up and down an essential national corridor.

"That rail line is a vital part of our American economy, and it needs to be in a place where it is not at risk from hurricanes," says Brian Sanderson, deputy director in the Governor's Office of Recovery and Renewal in Mississippi.

There are 170 rail crossings - many without a barrier - that run through 10 cities in one of the South's largest and fastest growing economic areas. "It's not a railroad to nowhere; it's a rail line to safety," he adds.

The Senate takes up the bill that includes the Gulf rail project next week. More than $14.3 billion over the White House request, it includes other earmarks such as $1 million for an air trade show in Las Vegas and $1.9 million to promote art in West Virginia. "This ... bill threatens to become another symbol of irresponsible runaway spending," says Brian Riedl, a senior fellow at the Heritage Foundation.

Will voters care come November? "If voters are upset about $3 gas and healthcare costs, they're ripe for a message that emphasizes fiscal discipline," says Amy Walter, a congressional analyst for the Cook Political Report.