The Trump administration is at least two months away from starting construction of prototypes for a wall along the Southwest border, underscoring the difficulties the White House faces making good on one of the president's key campaign promises.
Customs and Border Protection still has not signed any contracts to build prototypes of new barriers, a first step in plans to design and erect a wall along the 2,000-mile Mexico border, Ronald Vitiello, acting deputy commissioner at the agency, told reporters Tuesday.
He said construction of four to eight prototypes could begin by late summer. All will be built near the San Diego-area border fence.
"We're evaluating proposals now," he said. "We think it's summer. It's kind of hard to nail down."
During the campaign, Donald Trump promised that construction of the wall would begin almost immediately and that Mexico would pay for it.
But Mexico's government has dismissed that notion, and many in Congress are wary of footing the cost — anywhere from $15 billion to $66 billion, depending on who is providing the estimates. A Homeland Security document estimated the cost at $21.6 billion.
At the pace of construction planned for next year, it would take more than 15 years to build a wall along more than 1,300 miles of border, much of it rugged and remote, that don't have physical barriers now.
Vitiello said it's impossible to know whether that pace will pick up, saying it depends on how much and how quickly the agency gets money for surveys, engineering, designs, procurement and construction.
President Trump's budget request to Congress next year includes $2.6 billion for border security. Part of that will help build 74 miles of new wall, much of it in the Rio Grande Valley in Texas, and buy ground sensors, cameras and other technology to stop illegal crossings.
Scaling up to hundreds of miles will present huge engineering, logistical and legal challenges.
Much of the border barrier would cross private property, snaking through floodplains and over mountains. The Department of Justice has proposed hiring a dozen new lawyers just to work on eminent domain cases.
Many critics have questioned whether the hugely expensive construction project is a cost-effective way to secure the Southwest border.
The number of people caught illegally crossing the border has dropped dramatically since Trump took office, from 31,581 in January to 11,126 in April, before rising to 14,535 in May.
Vitiello said the San Diego border was a good example of how barriers could make a difference: In 1992, there were 560,000 arrests of undocumented migrants there, about half the total for the entire border. Last year it was 68,000, he said.
Vitiello also said the agency has concluded that it's not practical or necessary to build barriers along at least 130 miles of border, including the steep canyons of the Big Bend Valley and the lake region near Del Rio, both in Texas.
"It's not necessary; the natural barrier already slows people down," he said.
In documents requesting bids from private companies, the Department of Homeland Security asked for proposals to build 30-foot-high concrete walls with features intended to discourage climbing and tunneling, as well as tampering or damage.
Trump, however, has added confusion to the design process, potentially slowing any construction.
In a speech last week in Iowa, the president declared that he may want to build the wall with solar panels so it "creates energy and pays for itself."
Vitiello said no one at the White House consulted with Customs and Border Patrol before that announcement. But he said some companies previously had pitched solar panels.
"We're leaning on industry to innovate, to show us what they think is possible and doable and innovative," he said.
Construction of the wall remains a divisive political issue, with fierce resistance in some communities.
In California, Democratic state legislators have moved to blackball companies that participate in the wall construction. One proposal, Senate Bill 30, would ban those firms from receiving any new or extended contracts with the state.