It has recently been reported that several city and state governments are considering laws and ordinances to blacklist federal contractors because they wish to work on bolstering the infrastructure at the southern border, including construction of a wall.

For example, the California State Senate considered legislation that would force the state to drop its investments in any companies involved in border security projects. Earlier this year, the City Council of Austin, Texas, approved a resolution banning the city from conducting business with contractors working on the southern border wall. These aren’t the only examples of this discriminatory behavior, and I find this deeply troubling to say the least.

I have had countless conversations about our country’s illegal immigration problem with many of the people who live and work in Alabama’s Second District, and the overwhelming majority of individuals I’ve spoken with agree: When it comes to illegal immigration, our top priority must be securing the border. It is absolutely vital that we do this to put an end to individuals crossing into our country illegally. In order to strengthen the border infrastructure, we must have a qualified workforce and experienced businesses that are able to operate without discrimination or retaliation for simply following federal government contract directives of building a secure system – a wall – along our southern border.

This type of behavior is dangerous because when private companies are threatened with the looming possibility of discrimination of this kind, it can understandably cause them to hesitate to volunteer their work to play the many roles that the federal government asks them to play in delivering on the goods and services necessary to protect our national security interests, specifically as it relates to securing our border. Unless checked, these emboldened state and local officials will further discriminate against companies that perform any number of critical national security tasks on behalf of our federal government. These discriminatory measures could easily multiply as state and local officials attempt to deter the construction of anything they consider offensive to their own beliefs.

While this situation is very unsettling, I am pleased to report that the Department of Justice is fully aware of what’s going on and plans to take action. I recently had the opportunity to discuss this matter with Attorney General Jeff Sessions when he testified before the Commerce, Justice, and Science Appropriations Subcommittee, on which I am proud to serve. During the hearing, I asked our Attorney General when and how the Justice Department plans to respond to these state and local governments about their discriminatory behavior. I appreciated his direct response: “We will not accept it. This is an unbelievable assertion of power. We don’t believe it is sustainable legally, and we will challenge it wherever there is a case to be proven.”

Congress, and only Congress, has the power to change or alter our immigration laws – not various local or state governments. By discriminating against these companies based on their personal opposition to the construction of a border wall, these governments are undermining the constitutional Supremacy Clause of the federal government.

I appreciate our Attorney General and his diligent work to combat our serious illegal immigration problem, and I will continue to tackle the issue in every way I can as your representative in Congress. For now, Attorney General Sessions and I have made our position clear: Discriminating against companies for their important work to strengthen border security as directed by the federal government is unacceptable, and we will fight it every step of the way.

U.S. Rep. Martha Roby is a Republican from Montgomery.