WASHINGTON — The Trump administration late Friday night took the first steps toward fulfilling a campaign promise, requesting proposals to build a “physically imposing” wall on the border with Mexico.

The request follows the release on Thursday of President Trump’s first budget proposal, which includes money to pay for planning and construction of the wall. The budget calls for $2.6 billion to be spent on “tactical infrastructure” and other security technology at the border, including money to plan, design and begin building the wall.

The request for proposals adds further details about the Department of Homeland Security’s plans for the wall, including the kind of construction materials to be used, its height and even plans to make it aesthetically pleasing.

The structure would also have anti-climbing features and would be designed to prevent tunneling underneath it.