WASHINGTON — A much-ballyhooed White House proposal to boost domestic manufacturing might be stuck in the pipeline.

More than a year after President Donald Trump demanded that oil and gas pipelines built in the U.S. be constructed with U.S.-made steel — roiling the energy industry in Texas and beyond — there is little evidence that the Trump administration is close to making that idea a reality.

A July deadline for the U.S. Commerce Department to produce such a plan went by without the release of any details. Trump has dropped the idea from his speeches, where it was once a prominent fixture. And groups tracking the proposal say it has just fallen off the radar.

“With little explanation, it has vanished,” said Scott Paul, president of the Alliance for American Manufacturing, which supported Trump’s “Buy American” effort.

That inaction could reflect concerns that the mandate would be unfeasible and potentially in violation of international trade law. Or it could result from resistance by companies like Dallas’ Energy Transfer Partners, which called the idea “well-intentioned” but “unworkable.”

But the jam doesn’t mean the push is altogether dead.

The Commerce Department, which didn’t respond to requests for comment, could always press ahead. The White House’s plan for a $1.5 trillion infrastructure package could be a new vehicle. And some trade cases involving steel imports could offer an indirect way to address the issue.

“We are always keeping ourselves ready for any sort of movement by the administration,” said Tori Whiting, a trade expert at the conservative Heritage Foundation, which has opposed the mandate. “And we are going to be ready and alert to call balls and strikes.”

Trump wasted little time as president in making energy pipelines a focus.

In his first week on the job, the Republican thrilled party faithful and industry boosters by signing executive actions to advance Energy Transfer Partners’ contentious Dakota Access pipeline and TransCanada’s long-delayed Keystone XL pipeline.

Trump, however, also insisted that an extra “one-sentence clause” be included.

“If we’re going to build pipelines in the United States, the pipe should be made in the United States,” he said, explaining his dismay that big chunks of the steel used in those projects were not made in America.

His resulting presidential memo asked the commerce secretary to create a plan by late July to require all new and expanded American pipelines to use U.S. materials and equipment to the “maximum extent possible” and to the “extent permitted by law.”

And that request sent shock waves through the industry.

While “Buy American” is a well-established mechanism for federal procurement efforts or federally funded projects like highway overhauls, such a mandate on oil and gas pipelines would meddle deep into the business of privately funded endeavors.