U.S. Customs and Border Protection has asked contractors for help making President Donald Trump's border wall more difficult to climb over and cut through, an acknowledgment that the design currently being installed across hundreds of miles of the U.S.-Mexico boundary remains vulnerable. 

The new Request For Information notice that CBP posted gives federal contractors until June 12 to suggest new anti-breaching and anti-climbing technology and tools, while also inviting proposals for "private party construction" that would allow investors and activists to acquire land, build a barrier on it and sell the whole thing to the government.

Trump continues to campaign for reelection on a promise to complete nearly 500 miles of new barrier along the border with Mexico by the end of 2020, but administration officials have scaled back that goal in recent weeks. The president has ceased promoting the $15 billion barrier as "impenetrable" in the months since The Washington Post reported smuggling crews have been sawing through new sections of the structure using inexpensive power tools.

In a statement, CBP officials said their new request for information - first reported by the KJZZ Fronteras Desk in Arizona - does not amount to an admission that the current design is inadequate or flawed.

"We have an adaptive adversary; regardless of materials, nothing is impenetrable if given unlimited time and tools," the agency said. "Walls provide the U.S. Border Patrol (USBP) the ability to slow and stop potential crossings. That means building wall will deter some people from attempting to cross, while slowing the efforts of those who still try."

The public notice is the first indication CBP officials do not believe the steel bollard design they selected from prototypes in 2017 is sufficiently formidable to achieve that goal. The primary design, consisting of 30-foot-tall steel bollards topped with flat metal anti-climb panels, is now being installed by private contractors at multiple locations along the border.

"This is the most sophisticated border wall system we have ever built, but we will never disregard innovative and creative ideas that could continue to enhance border barriers," CBP said.

Trump is expected to attend a ceremony in Yuma, Ariz., next week to mark the completion of the barrier's 200th mile, according to officials who were not authorized to describe the plans.

CBP has not said publicly how often smuggling crews have breached or attempted to breach the structure. Records obtained by The Post via the Freedom of Information Act indicate there were 18 breaches in the San Diego area during a single one-month period last fall. The San Diego areas has some of the most formidable barriers along the entire border, and construction of new double-layered fencing there is largely complete.

Smuggling crews have nonetheless managed to saw through the steel bollards using commercially available demolition tools such as reciprocating saws with inexpensive metal-cutting blades. Others have fashioned long, improvised ladders out of cheap metal rebar. More athletic border-jumpers have been seen using rope ladders to climb up the wall, sliding down the other side by gripping the bollards like a fireman's pole.

The CBP request for information says the agency is looking for new ways to stop them.

"Customs and Border Protection (CBP) recognizes that industry, other agencies, and other private entities may have interesting, innovative, and useful ideas that could be implemented to enhance and or improve mission essential operational deterrent capabilities related to the anti-climb/anti-cut features of the border wall and persistent impedance," it reads.

Such proposals could include sensors and cameras that would provide early warnings for climbing and breaching attempts, as well as "advanced paint technology that would enhance the ability of thermal sensors to recognize wall jumpers and improve detection."

Trump maintains a keen interest in the aesthetics and design elements of the barrier, and his shifting preferences have repeatedly left border officials and military engineers struggling to adjust his tastes to the operational and geographic realities of the U.S.-Mexico border.

In recent weeks, the president has once more insisted the barrier should be painted black, telling aides it will absorb more heat from the sun and deter climbing by scalding the hands of would-be fence jumpers. The black paint will drive up construction costs by at least $500 million, according to government estimates, and skeptics have pointed out that the black paint will increase maintenance costs. That, and climbers could simply use gloves to protect their hands.

The language in the CBP request for information about "private-party construction" appears specifically geared to the efforts of the group "We Build the Wall," led by former Trump adviser Stephen K. Bannon and other prominent conservative activists, including Kansas senate candidate Kris Kobach.

The group says it has raised or received $25 million in donations to build new barriers on private land. The CBP request appears to be the first indication that the government is considering mechanisms to obtain and incorporate those new sections of private barrier into Trump's broader effort.

"CBP recognizes that private entities and nongovernmental organizations also have an interest in supporting the mission of border protection, by deploying private wall solutions," the CBP notice states. "Mainly, those parties that can arrange private financing, and private acquisition of land may have an interest in devising a wall structure that is consistent with government specifications."

The CBP request also identifies 30 locations totaling roughly 250 miles of border where private barriers could be built for sale to the government.

We Build the Wall has completed at least two sections of private barriers in Texas, using North Dakota-based Fisher Industries to perform the work and acquire the land. The president has urged the U.S. Army Corps of Engineers to give border contracts to the company, whose CEO is a prominent GOP donor and Trump booster.

Fisher last month secured a $1.3 billion contract to install 42 miles of black-painted new barriers in Arizona. The company's first and only other award, for $400 million, is currently under audit by the Inspector General of the Department of Defense, a review initiated after Democrats alleged improper White House interference in the procurement process.