WASHINGTON ― The Trump administration still has no idea what the president’s promised “impenetrable, physical, tall, powerful, beautiful southern border wall” will look like. But it’s unlikely to be an actual wall “from sea to shining sea,” Homeland Security Secretary John Kelly said Wednesday.

Speaking before the Senate Homeland Security and Governmental Affairs Committee, Kelly said his department would do whatever makes the most sense to secure the border, even if that means adding fencing and technology rather than constructing a wall.

“The president has told me, ‘Kelly, go do it.’ We need to protect the southwest border in any way that that makes sense,” Kelly said. “I have a lot of elbow room.”

He added: “The president knows that I’m looking at every variation on the theme and I have no doubt when I go back to him and say, ‘You know boss, wall makes sense here, fencing ― high-tech fencing ― makes sense over here, technology makes sense over here,’ I have no doubt that he will go tell me to do it.”

Building a “real wall” was a central promise of President Donald Trump’s campaign ― and one that almost certainly won’t happen in the way he said it would. The president and his surrogates have been laying the groundwork for this retreat for months, saying the “wall” wouldn’t need to span the entire border, could be technological, and could supplement existing fencing, even though the president has criticized that fencing and publicly claimed a new wall was necessary. If the muddle is successful, it would mean Trump could add some border fencing and technology, and then claim victory for creating his wall without actually building the new structure he promised.

Kelly said before his confirmation as homeland security secretary that he did not think a wall itself would resolve border security issues, and has said since that in some areas, physical barriers would be unnecessary or impractical.

On Wednesday, he again said he doesn’t expect to build a 2,000-mile wall, based on recommendations from Customs and Border Protection agents about what they think would help prevent illegal entries.

“It’s unlikely that we will build a wall or physical barrier from sea to shining sea, but it is very likely ― I’m committed to putting it where the men and women say we should put it,” Kelly said.

He said he wasn’t sure what such a project would cost, or what it would look like. The department is still in an early phase of the process ― contractor submissions for border wall prototype proposals ended at the end of Tuesday.

“What it’ll look like, how tall it will be, how thick it will be, what color it will be, is yet to be determined,” Kelly said. “All we know is that physical barriers do work if they’re put in the right places.”