A crowdfunding effort to build a wall at the U.S.-Mexico border unveiled its progress over the weekend, quelling skepticism from some supporters of the $22 million fundraising campaign. But the project's legality is now being questioned by a local mayor, who issued a cease-and-desist order Tuesday.

Brian Kolfage seeks to fill gaps along the "porous" southern border, which he says leaves the United States "vulnerable to attack." When GoFundMe offered refunds in January after Kolfage fell short of his $1 billion goal, he channeled the money to a nonprofit that aims to construct wall segments on private property.

Photos and videos of construction on the barrier, plastered to social media Monday by We Build The Wall Inc., seem to have appeased those who doubted whether the project was actually happening. The group now claims it is close to completing a half-mile stretch of wall in Sunland Park, New Mexico, and last week, The Washington Post observed employees from North Dakota-based construction company Fisher Industries prepping a work site near the location. In recent months, President Donald Trump has urged the U.S. Army Corps of Engineers to give a border wall contact to the same firm, The Post reported.

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"They said it was impossible, we proved them wrong," We Build The Wall wrote on Facebook. " . . . This new wall is the first of more to come, and we couldn't of [sic] done it without your gracious donations."

Kolfage bragged in a Tuesday afternoon post that the wall segment - built on a stretch of land that is privately owned by a brick company - had already proven effective in deterring migrants. He professed without evidence that the area was a popular "smuggling route for the cartels" that attracted thousands of migrants per day.

Former White House chief strategist Steve Bannon and Kris Kobach, the former Kansas secretary of state - both of whom serve as advisers to the group - spoke to CNN at the Sunland Park construction site. Bannon said the half-mile barrier will combine two 21-mile segments of existing fencing, and further suggested U.S. Customs and Border Protection told We Build The Wall that location was the "No. 1 most important mile to close."

A CBP spokesman told CNN Kolfage's project was "not connected" to their efforts.

We Build The Wall has repeatedly said their project will be significantly less expensive than President Donald Trump's proposed border wall. Kobach told CNN the half-mile wall segment would cost between $6 million and $8 million. In January, Kolfage estimated the wall segments would be priced at $2 million to $3 million per mile.

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Kolfage and his team did not return a request for comment Tuesday. Jeff Allen, who reportedly owns the private property where the barrier is being built, told CNN that We Build The Wall is doing an "incredible job."

"I have fought illegals on this property for six years," he told the network. "I love my country, and this is a step in protecting my country."

Excitement for the project was again dampened Tuesday, however, when local officials alleged those involved in its construction lacked the necessary permits. At a news conference, Sunland Park Mayor Javier Perea said officials were denied a chance to inspect the site last week, and that the property's owner had submitted documents to build the wall that typically take months, not days, to get approved.

The barrier also surpasses the city ordinance's maximum allowed height of six feet, Perea added, meaning the wall is "not in compliance with city ordinance."

City officials issued a cease-and-desist order Tuesday as lawmakers condemned construction efforts. In a statement to the Silver City Sun News, El-Paso-based Democrat Rep. Veronica Escobar took particular aim at Kobach and Bannon.

"It's deeply disturbing when outsiders, like Kris Kobach and Stephen K. Bannon, come in and use our community and people as a backdrop to further their racist agenda," Escobar said. "It's even more disturbing that a business in our community is furthering this xenophobic narrative. While this wall may be necessary fuel for the president's political campaign, it will not prevent people from seeking asylum."

New Mexico Democratic Gov. Michelle Lujan Grisham, in a statement to the New York Times, argued the half-mile wall would do little to bolster border security.

"To act as though throwing up a small section of wall on private land does anything to effectively secure our southern border from human and drug trafficking or address the humanitarian needs of the asylum seekers and local communities receiving them - that's nonsense," Grisham wrote.

Responding to the backlash in a tweet, Kolfage disputed claims he lacked the necessary permits. He'd been given the "green light to build" from city officials, he said.

Perea and a city spokesman did not immediately return messages requesting comment Tuesday evening. In a statement to ABC affiliate KVIA, We Build The Wall again contended that it was in compliance with local regulations.

"We've had members from Sunland Park city government out to inspect the site and to witness the first concrete pour," the statement read. "We believe this is a last-ditch effort to intimidate us from completing this historic project by a local government with a long history of corruption problems."

A southern border wall, paid for by Mexico, was once the hallmark promise of Trump's presidential campaign - but he's faced resistance at nearly every turn. Most recently, a judge temporarily blocked Trump from using billions in funds not appropriated by Congress for wall construction.

The president rebuffed the judge's Friday decision, stating it was "a ruling against Border Security and in favor of crime, drugs and human trafficking."

Enter Kolfage, who on Monday wrote he had other walls "lined up" and ready to go, declined to specify where. He's previously refused to detail site locations, indicating he fears potential intervention from the ACLU and "other liberal groups."

"We're not stopping until we're done," Kolfage wrote Monday.

This article was written by Michael Brice-Saddler, a reporter for The Washington Post.