U.S. Presidential candidate Elizabeth Warren along with fellow Senators Richard Blumenthal and Bill Cassidy wrote a letter to Alphabet’s Google on Wednesday to raise questions about its access to the health records of Americans.

Warren and Blumenthal, who are Democrats, along with Cassidy, a Republican, were focused on a business partnership that Google formed with Ascension Health.

Ascension, which operates 150 hospitals and more than 50 senior living facilities across the United States, is Google’s biggest cloud computing customer in healthcare, in a deal giving it access to datasets that could help it tune artificial intelligence (AI) tools.

The lawmakers asked Google to provide information about other health systems which provide information to Google, whether Ascension clients will be allowed to opt out of the project and whether the data be used for advertising, among others.

Google said that it was happy to answer questions about the project.