Holdren served as one of President Bill Clinton‘s science advisors (PCAST) from 1994 to 2001.[2] Eight years later, President Barack Obama nominated Holdren for his current position as science advisor and Director of the Office of Science and Technology Policy in December 2008, and he was confirmed on March 19, 2009, by a unanimous vote in the Senate.He testified to the nomination committee that he does not believe that government should have a role in determining optimal population size and that he never endorsed forced sterilization. (…)

Overpopulation was an early concern and interest. In a 1969 article, Holdren and co-author Paul R. Ehrlich argued, „if the population control measures are not initiated immediately, and effectively, all the technology man can bring to bear will not fend off the misery to come.“[28] In 1973, Holdren encouraged a decline in fertility to well below replacement in the United States, because „210 million now is too many and 280 million in 2040 is likely to be much too many.“[29] In 1977, Paul R. Ehrlich, Anne H. Ehrlich, and Holdren co-authored the textbook Ecoscience: Population, Resources, Environment; they discussed the possible role of a wide variety of means to address overpopulation