WASHINGTON (NewsNation Now) — President-elect Joe Biden has picked California Attorney General Xavier Becerra to be his health secretary, putting a defender of the Affordable Care Act in a leading role to oversee his administration’s coronavirus response.

Separately, Biden picked a Harvard infectious disease expert, Dr. Rochelle Walensky, to head the Centers for Disease Control and Prevention.

The choice of Becerra, 62, a Latino former congressman, comes as Biden faces more pressure to add diversity to his cabinet appointments, including complaints from the Congressional Hispanic Caucus about the number of Latinos.

Becerra will lead the health agency as officials struggle to contain a resurgence of the coronavirus, including record infections and a daily death toll that has exceeded 2,000 in recent days, and to prepare for a mammoth effort to vaccinate Americans against the virus.

Biden and Vice President-elect Kamala Harris will formally introduce the health team nominees and appointees at an event in Wilmington, Delaware, on Tuesday.

Biden is expected to roll out more members this week as he fills in key roles in his cabinet ahead of taking office on Jan. 20. He already has announced top nominees for his national security and economic teams.

Biden is also expected to nominate Rochelle Walensky, chief of infectious diseases at Massachusetts General Hospital, to run the U.S. Centers for Disease Control and Prevention, a different person familiar with hiring for the president-elect’s health team said.

Biden already has asked Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and a member of Trump’s coronavirus task force, to stay on as chief medical adviser.

The former vice president also has named Jeff Zients, an economic adviser touted for his managerial skills, as a coronavirus “czar” to oversee an unprecedented operation to distribute hundreds of millions of doses of a new vaccine, coordinating efforts across multiple federal agencies.

Dr. Marcella Nunez-Smith will serve as COVID-19 Equity Task Force chair advising the president-elect on a “whole-of-government” effort to reduce COVID-19 disparities in response, care and treatment, including racial and ethnic disparities,” according to a release by the Biden-Harris transition team.

Biden picked Vivek Murthy, a physician and former surgeon general who has gained prominence in recent months as co-chairman of Biden’s advisory board dealing with the pandemic, to return for a second term as surgeon general.

Natalie Quillian will serve as deputy coordinator of the COVID-19 response. Quillian was a former White House and Pentagon senior advisor and played an instrumental role in the Obama administration’s response to the opioid epidemic.

Becerra served as a Democratic U.S. representative from 1993 to 2017 before moving back to his home state to become attorney general. In that post, he succeeded Vice President-elect Kamala Harris.