He is currently an advisory board member of “We Build the Wall Inc.” a nonprofit group that has collected more than $12 million toward the effort. Mr. Kobach says the group has obtained the presidential seal of approval for the private initiative.

President Trump gave the undertaking his “blessing” in a telephone conversation Wednesday night, according to Mr. Kobach.

The White House press office did not respond to requests for comment.

Mr. Kobach, 52, says the group will begin construction soon on its first section of the wall on donated property, likely in Texas, and that the work can be completed cheaply and efficiently by the private sector.

After raising nearly $20 million, the organization was forced to contact donors because it hadn’t reached its initial goal of $1 billion. At that point, contributions would be automatically returned to donors unless they opted back in. Mr. Kobach said that efforts to retain contributors had been very successful, with 94 percent of those contacted transferring the money into the new effort.

Mr. Kobach, who is considering a 2020 run for the United States Senate seat being vacated by Pat Roberts, said he is currently an unpaid adviser to the organization but added that he might take a major administrative role as the project grows. Asked whether he would be compensated at that point, Mr. Kobach said he was not sure.

Q. I understand that you’re on the board of an organization that’s promoting a private wall. Can you tell me what the goal is?

A. The goal is to facilitate construction of a border wall on private land with private funds along the southern border in conjunction with federal government efforts to construct the wall.

Have you done any work to see how much that’s going to cost?

We believe we can build the wall, or build sections of the wall, for well under half the price that the federal government is projecting and perhaps as low as a quarter of the price. Quite often the federal government purchases things at prices higher than individuals in the private marketplace.

Do you have a location in mind right now? Do you have landowners who will donate land for this?

We have landowners who are inviting us already. We’ll be hopefully breaking ground within weeks, but I don’t want to give the names yet. We haven’t selected where we’re going to start. It doesn’t require the donation of a large amount of land. The landowner retains the land. It’s not like we build the wall and take possession of the land.

Do you think there’s a groundswell of support for this?

I do think there’s a groundswell of support. It’s an objective that people conceive of very easily. It’s not rocket science. It’s not super high technology to construct border barriers.

Democrats have proposed other kinds of mechanisms for securing the border — technology, drones, radar.

We already have drones and sensors on the border and they seem to think that having more is adequate. Drones don’t stop people from coming across the border, they merely tell you that someone is coming across the border. I don’t think the people who are proposing the drones only are serious about stopping the flow of illegal immigration.

What are people in Kansas telling you?

In Kansas, support for the wall is very strong. We haven’t done any polling or outreach on the specific question of “We Build the Wall” organization, but certainly support for building a wall or a series of barriers on the border is very high.

Have you reached out to people at Homeland Security? Are they on board with this idea?

I have not personally but I believe others in our organization have. We intend to cooperate and to the extent possible collaborate with the Department of Homeland Security. The objective is to assist and to create a system of sections that ultimately connect and serve one another.

I talked with the president, and the “We Build the Wall Effort’’ came up. The president said ‘the project has my blessing, and you can tell the media that.’

Do you see this as an alternative to a federal project?

I see it as a supplement to a federal project. The $5.7 billion would not secure the entire border, even if Democrats gave the president everything he’s asking for in the current discussion. There will be hundreds of miles of gaps collectively that still wouldn’t be secured. So these private efforts will help supplement and fill in the gaps that still exist after, if and when the president is able to complete the sections of wall that he’s proposing.

Some people might say securing the border is a government function just like air traffic control.

It is correct that securing the border is a government function, but when the government fails, it has a specific and significant impact on individual landowners. So the failure to secure the border affects me in Kansas indirectly and it affects you in New York indirectly. But the landowner who has the ranch right on the border is affected in a way that is 1,000 percent greater than what you and I would experience. The biggest effects are litter and security. The traffickers, as they’re bringing their migrants through, they’re constantly dumping clothing, food containers and trash on the ranchers’ land. And then there’s an environmental impact. But the biggest impact for individual landowners is security.

Sounds like you’re looking at this from the standpoint of private property rights and the rights of private landowners?