— In an office building near the U.S. Capitol last week, energy company representatives huddled with federal bureaucrats and Louisiana utility managers to debate the fate of the Midla natural gas pipeline.

Far less controversial than the proposed Keystone XL pipeline from Canada to the Gulf, Midla nonetheless has attracted the close interest of Louisiana senators and representatives in Washington — in a case that suggests that, in Congress, ideological purity can founder on the shoals marked: “All politics are local.”

The Midla pipeline was built 90 years ago across the 200 miles from the Monroe gas fields to Baton Rouge. Pipeline owner American Midstream says the deteriorating line is leaky and dangerous. The company says it has lost millions on Midla in recent years.

Continuing to patch up the existing pipeline is a nonstarter, the company says. But it says it will work with Atmos Energy and the pipeline’s other utility customers to develop alternatives, such as replacing sections or delivering compressed natural gas by truck.

But American Midstream says the utilities have refused to sign the long-term contracts needed to justify the investments. Atmos says that’s true: It thinks American Midstream should seek to recover its costs through the normal, government-regulated, rate-setting process.

So American Midstream has applied to the Federal Energy Regulatory Commission for the required government permission to abandon the pipeline.

Not so fast, say several members of the Louisiana delegation.

The issue brings together U.S. Sen. Mary Landrieu, a Democrat, with U.S. Sen. David Vitter and two of his fellow Republicans, U.S. Reps. Bill Cassidy, of Baton Rouge, and Vance McAllister, of Swartz.

“We are concerned that the public interest will be disserved by the pipeline abandonment,” Cassidy and McAllister wrote to federal officials. “Replacement of the pipeline could cause unjust and unreasonable rate increases for Midla’s customers, who historically paid higher rates to accommodate the pipeline’s maintenance costs.”

Cassidy and Vitter have asked FERC to look into how the company spent those previous rate payments and at how safe the line is now.

In a letter to FERC Acting Chairman Cheryl LaFleur, Landrieu said, “I am writing to express in the strongest possible terms my opposition to the application ... to abandon the Midla pipeline ...”

Landrieu is uniquely positioned to compel FERC’s attention: As chairwoman of the U.S. Senate Energy and Natural Resources Committee, she presided over a recent hearing on LaFleur’s reconfirmation to a seat on the commission.

But Landrieu stands apart among the Midla-istas for another reason: As a center-left Democrat, her call for the government to override a private business in regulating the market does not constitute a sharp break with her ideological principles.

That’s not so much the case for the Republicans, who all espouse conservative doctrine, with its tenets of smaller government, deregulation and free-market economics.

“Senator Vitter believes that the federal government is too big, too bloated, and too involved in Louisianians’ daily lives,” Vitter’s website says. “Senator Vitter has fought against ... government agencies that destroy jobs by piling burdensome regulations on small businesses.”

To be sure, American Midstream is not a small business. And a Vitter spokesman said Vitter’s communications with FERC have focused on requests for further investigation.

On a campaign website, McAllister says, “I will stand up and fight every single day to ... stop the march of big government into our lives.”

But McAllister said his sympathy lies with the hard-pressed rural residents along the pipeline’s route who rely on Midla for natural gas.

“It’s not the American way that you wake up one day, and because the wealthy want to get wealthier, they cut you off,” he said.

Cassidy’s website for his campaign to unseat Landrieu this fall includes an endorsement from Republican U.S. Sen. John Cornyn, of Texas, who says Cassidy “would be friendly to the private sector and the free enterprise system.”

Cassidy said he doesn’t see FERC’s role as particularly intrusive.

“I, as a free-market conservative, see the role of the government to set, if you will, the out-of-bounds limits,” he said, “and enterprise has to take place within those boundaries.”

Maybe Vitter, Cassidy and McAllister are fans of Ralph Waldo Emerson, who said, “A foolish consistency is the hobgoblin of little minds.”

Gregory Roberts is chief of The Advocate Washington bureau. His email address is groberts@ theadvocate.com