Sen. Elizabeth Warren is putting pressure on Capital One to answer questions about the recent data breach that affected more than 100 million of the bank’s customers.

In a letter on Wednesday to Richard Fairbank, Capital One’s chief executive, the Massachusetts Democrat and 2020 presidential candidate requested information on how the breach was conducted and when the bank plans to notify customers whose data — including possibly their Social Security numbers — was taken in the breach.

[How Elizabeth Warren learned to be a candidate]

“The public deserves to know exactly what the company plans to do to ensure that consumers’ accounts and application information are protected from the consequences of Capital One’s security failures,” Warren wrote to Fairbank.

In her letter, the senator raised concerns that the company promised to notify individuals who were affected but did not offer a timetable for doing so or an explanation of who it considered an affected customer.