President Trump's border wall project has reportedly hit a road block.

Trump issued an executive order in January calling to start the U.S.-Mexico border project with "existing funds" of the Department of Homeland Security.

But Reuters reported Wednesday that the department only came up with $20 million that can be redirected to the multibillion-dollar project. That sum would be able to finance contracts for prototypes, but would not cover breaking ground on the project.

The agency reportedly said it would reallocate about $5 million from a fence project in Arizona that came in under budget and $15 million from a project to install cameras on top of Border Patrol trucks.

TRUMP DEFENDS BORDER-WALL PLAN, SAYS HE WON'T ALLOW 'LAWLESS CHAOS'

Reuters viewed the document prepared by the agency and distributed last week to congressional budget staff.

The Government Accountability Office estimated a wall would cost on average $6.5 million a mile for a fence to keep out people who try to enter on foot and $1.8 million a mile for vehicle barriers. There are currently 354 miles of pedestrian fencing and 300 miles of vehicle barriers.

The wall is reportedly expected to cost $21.6 billion – blowing far past earlier estimates. Trump initially said the wall could cost $12 billion.

The lack of funds in the agency would mean that the White House would have to convince Congress to grant the funds needed to start construction.

The border wall was Trump’s key campaign promise and his insistence that Mexico would pay for it was extremely popular among his supporters, sparking enthusiastic cheers at his raucous rallies.Though Trump has insisted Mexico will eventually pay the U.S. back, American taxpayers are expected to foot the bill.

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