Even as the Trump administration blocks his access to the government, President-elect Joe Biden forged ahead Tuesday with a key milestone in the transition of power, naming teams that will begin gathering information about federal operations.

Biden’s transition team has assembled a list of 500 experts in federal policy from diplomacy to space exploration who will form the backbone of his preparations to lead the federal government in January, learning from the workforce what to expect at every agency on personnel, technology, policy and program matters.

“It’s about getting the Cabinet leaders ready to lead, equipping them with the information they need,” a Biden transition official said in advance of the public rollout.

The teams that go into federal agencies are a tradition of presidential transitions. But the Biden teams will not make formal contact with Trump appointees and the career staff now in government because the outgoing administration has not yet released transition resources and allowed access to agencies, a decision that has led to a standoff with the Biden transition.

The Post's Lisa Rein explains how the Trump administration is adding challenges to the transition process for President-elect Joe Biden. (The Washington Post)

However, transition officials stressed that they are working through informal channels to learn what’s going on in the government, talking with think tanks, labor and nonprofit groups and those who previously served at federal agencies.

“We may not be making formal contact, but the transition work is continuing to move full speed ahead,” said a Biden transition official, speaking on the condition of anonymity to discuss their planning efforts.

Besides preparing Biden and Vice President-elect Kamala D. Harris to take over the government, the teams will serve as “ambassadors to the career staff” of 2.1 million, the official said, “folks who are our partners in solving the world’s problems.” The reference drew a contrast with the incoming Trump administration four years ago, whose “landing teams” established a mistrust of career civil servants at many agencies.

The vast majority of the Biden team members will volunteer their time, transition officials said.

An array of diverse and long-established experts in the federal government will lead or hold prominent roles on the teams, ranging from state and local officials with track records in key policy areas to former diplomats and other senior officials from the Obama administration.

Transition officials stressed that the diversity of these initial emissaries to the government reflect the Biden team’s commitment to a diverse workforce at all levels. Some are likely to stay on as political appointees, while others will return to their roles outside government, following a long tradition in new administrations.

These are some officials who will have prominent roles in the effort and the agency they will work with:

 ●Kiran Ahuja​, Office of Personnel Management. Ahuja is chief executive officer of Philanthropy Northwest, the regional philanthropic network for Alaska, Idaho, Montana, Oregon, Washington and Wyoming. She served as chief of staff at the personnel agency from 2015 to 2017.

●Andrea Flores​, Department of Homeland Security. Flores, an attorney, is deputy director of immigration policy for the American Civil Liberties Union’s equality division. She previously worked for the secretary of homeland security.

●Rahul Gupta​, Office of National Drug Control Policy. Gupta served as the West Virginia health commissioner, leading the state’s opioid crisis response efforts and launching a number of pioneering public health initiatives to identify high-risk infants.

●Michelle Howard​, Department of Defense. Howard is former vice chief of naval operations and former commander of naval forces in Europe and Africa. She was the first Black woman to command a Navy ship and the first woman promoted to the rank of four-star admiral in the U.S. Navy.

●Justin Jackson, ​CIA. A 28-year veteran of the agency, Jackson is former deputy director of the National Clandestine Service, and at the time of his retirement was the highest ranking Black American at the agency.

●Monique King-Viehland​, Department of Housing and Urban Development. King-Viehland was the first African American executive director of the Community Development Commission and Housing Authority of the County of Los Angeles. She now directs state and local housing policy at the Urban Institute.

●Chris Lu​, Department of Labor. From 2014 to 2017, he was deputy secretary of labor. He also served as the Obama administration’s White House Cabinet secretary, the president’s primary liaison to the federal agencies.

●Pamela Melroy, NASA. Melroy is a former astronaut, retired U.S. Air Force colonel and test pilot and, as commander of NASA’s STS-120 team, the second woman to command a space shuttle mission.

●Geoffrey Roth​, Department of Health and Human Services. Roth was a presidential appointee to the Indian Health Service and helped implement the Indian Health Care Improvement Act.

●Shawn Skelly​, Department of Defense. Skelly was former special assistant to the undersecretary of defense for acquisition, technology, and logistics, and coordinator of the Department of Defense Warfighter Senior Integration Group. Skelly is the first transgender veteran to be appointed by a president of the United States.

●Ellen Stofan, NASA. Stofan is a former NASA chief scientist with more than 25 years’ experience in space-related organizations and a deep research background in planetary geology. She also served as chief scientist for the New Millennium Program at the NASA Jet Propulsion Laboratory.

●Karen Tamley​, Department of Housing and Urban Development. Tamley served 14 years as commissioner of the Mayor’s Office for People with Disabilities in Chicago. Earlier this year, she became president and chief executive of Access Living.

●Linda Thomas-Greenfield, ​Department of State. Thomas-Greenfield is a 35-year veteran of the Foreign Service and one of the most senior African American diplomats. She was assistant secretary of state for African affairs, leading the development and management of U.S. policy toward sub-Saharan Africa. Her Foreign Service career included an ambassadorship to Liberia from 2008 to 2012.

●Kevin Washburn, ​Department of Interior. Washburn is dean at the University of Iowa College of Law. Previously, he was a professor and served as dean at the University of New Mexico School of Law before joining the Obama administration as assistant secretary of Indian affairs.

●Geovette Washington​, Department of Commerce. Washington serves as senior vice chancellor and chief legal officer at the University of Pittsburgh. She was general counsel and senior policy adviser for the Office of Management and Budget and deputy general counsel for the Department of Commerce.