More information and application instructions are available at

https://www.whitehouse.gov/administration/eop/ostp/about/student. 

About OSTP: The Office of Science and Technology Policy advises the President on the effects of science and technology on domestic and international affairs. The office serves as a source of scientific and technological analysis and judgment for the President with respect to major policies, plans and programs of the Federal Government. About the Internship Program. Interns are accepted for one of three annual terms (Spring, Summer, or Fall), which each last no more than 90 days. The assignments provide educational enrichment, practical work experience, and networking opportunities with other individuals in the science and technology policy arena.