Sen. Cory Booker sent a letter to the heads of Homeland Security and Customs and Border Protection on Monday criticizing the newly rolled-out CBP One a mobile application that allows asylum-seekers to secure an appointment with CBP to get through U.S. ports of entry.

The United States is a beacon of hope for many around the world seeking safety and freedom. Unfortunately, migrants now have to contend with the CBP One app as the sole method to schedule asylum appointments, which has been plagued by technical problems since its introduction, Booker told HuffPost in an emailed statement.

We must ensure that our asylum process is just and equitable and protects those who are fleeing violence and persecution in a way thats consistent with our nations most fundamental ideals, he added.

The letter, first seen by HuffPost, comes as the Senate Judiciary Committee is set to hold an oversight hearing of DHS on Tuesday. Homeland Security Secretary Alejandro Mayorkas, one of the recipients of Bookers letter, is scheduled to testify.

CBP One launched in January as a part of the Biden administrations attempt to make border processing more efficient as Title 42 a public health order restricting immigration due to the coronavirus is set to expire in May. But CBP One, touted as DHSs official app , has been riddled with problems including technical and access issues for many families.

CBP releases a limited number of appointments each day, but migrants have reported a slew of issues while trying to secure those appointments. Many dont have cell phones that can access the internet or any phones at all. Poor connectivity and cell phone service were also a concern.

Even if the CBP One app was as efficient, user friendly, fair, and inclusive as possible which I hope one day it will be it would still be inherently discriminatory, reads Bookers letter, noting the resources an individual must have to successfully navigate the application.

When DHS first launched the app which is the sole method for Haitians, Nicaraguans, Cubans and Venezuelans to seek humanitarian parole it was also only available in English and Spanish, despite the fact the majority of Haitian nationals only speak Haitian Creole. In February, CBP added a Haitian Creole translation, but error messages still only appear in English, Booker notes. Appointments are inaccessible for anyone who cannot read.

Migrants are also required to snap a picture and enter how they are traveling either by land, plane, or boat but many have said the app failed to register their photos because they are Black or have darker complexions.

I remain deeply concerned that the technology used to capture faces with darker complexions has not been adequately tested and structurally disadvantages Black asylum seekers and urge the agency to address the issue, said Booker wrote.

Pregnant, nursing mothers and migrants with large families also have a host of issues with the CBP One process.

The senator said that although CBP and State Department officials have acknowledged the problems users are reporting, more improvements are needed.

While the expansion of opportunities for asylum seekers to have their claims heard is vital, I am disappointed that precautions were not taken before our government made the CBP One app the sole avenue to schedule appointments, said Booker.