The Office of Personnel Management released the following press release on February 6, 2020. Apparently postal employees are eligible to fill temporary positions with the U.S. Census Bureau:

2020 Census; Employees May Perform Short-Term, Temporary Work

The U.S. Census Bureau has begun its campaign to recruit hundreds of thousands of individuals across the country to fill a variety of temporary jobs, including recruiting assistants, office staff, census takers, and supervisory staff.  Because of these efforts, we are beginning to receive questions from currentFederal employees about accepting employment for the 2020 Census. In response to these questions, we are providing the following general information on dual employment – receiving pay for more than one position:

• In accordance with 13 U.S.C. 23(b), the Census Bureau may hire Federal employees upon approval of agency directors, but only for temporary, short-term work on the 2020 Census.
  • Please visit www.2020census.gov/en/jobs/faqsfor the list of agencies that currently have dual employment agreements for 2020 Census positions.  This list is found under the FAQ topic, “Special Circumstances for Candidates.”

• The statutory prohibition against receiving pay for more than one position found in 5 U.S.C. 5533(d) does not apply within the purview of 13 U.S.C. 23(b).  Therefore, current Federal employees who are hired for the 2020 Census may receive pay for this short-term, temporary work.

• Federal employees wishing to work with the 2020 Census may visit www.2020census.gov to apply.

The following comes to us from United States Census 2020

Note: see bottom of list for USPS

Will current federal employees be eligible to work as census takers?

Some federal employees working at agencies that have a dual employment agreement with the Census Bureau can work in 2020 Census positions. Under Title 13, United States Code, Section 23(b), the Census Bureau may hire federal employees upon approval of agency directors, but only for temporary, short-term work on the 2020 Census.

To be considered, you must complete a job application online. The agencies below have dual employment agreements for 2020 Census positions. Check back periodically for updates to this list.

• Agency for Global Media
• Agency for International Development
• American Battle Monuments Commission
• Corporation for National and Community Service
• Department of Agriculture
• Department of Defense (Civilian Employees)
• Department of Education
• Department of Energy
• Department of Health and Human Services
• Department of Housing and Urban Development (HUD)
• Department of the Interior
• Department of Labor
• Department of State
• Department of Transportation
• Election Assistance Commission
• Environmental Protection Agency
• Federal Deposit Insurance Corporation
• Federal Election Commission
• Federal Maritime Commission
• Federal Trade Commission
• General Services Administration
• Government Publishing Office
• Institute of Museum and Library Services
• Inter-American Foundation
• Library of Congress
• Millennium Challenge Corporation
• National Aeronautics and Space Administration
• National Archives and Records Administration (NARA)
• National Capital Planning Commission
• National Labor Relations Board
• National Science Foundation
• National Transportation Safety Board
• Nuclear Regulatory Commission
• Nuclear Waste Technical Review Board
• Office of Personnel Management
• Peace Corps
• Pension Benefit Guaranty Corporation
• Railroad Retirement Board
• Securities and Exchange Commission
• Small Business Administration
• Smithsonian Institution
• Social Security Administration
• Tennessee Valley Authority
• United States Postal Service
• Veterans Affairs

More information: Here