Promoting United States International Leadership in 5G Act of 2019 This bill directs the President to establish an interagency working group to provide assistance and technical expertise to enhance U.S. leadership in international bodies that set standards for 5th and future generations of mobile telecommunications (5G) technology, such as the International Telecommunication Union. The President shall also work to increase the participation of allies, partners, and the private sector. (International bodies develop standards for certain technologies, such as those used in wireless data transmission, to ensure interoperability between different companies' products. Stakeholders, such as companies that manufacture equipment that uses such technologies or companies that hold relevant patents, typically participate in the standards-setting process.) The interagency group shall report to and, on request, brief Congress on (1) its strategy to promote U.S. leadership in the standards-setting bodies relevant to 5G technology; (2) its strategy for diplomatic engagement with allies and partners to share security-risk information related to 5G; (3) China's activities in standards-setting bodies for 5G technology, including the scope and scale of such activities; and (4) a strategy for engaging with private-sector stakeholders, academia, and federally funded research and development centers to propose and develop secure standards for 5G technology.