WASHINGTON (AP) — Andrew Kohut, a leading pollster for more than three decades and founding director of the Pew Research Center, died Tuesday at age 73.

Kohut's son, Matthew, said his father died from a form of leukemia.

A president of The Gallup Organization from 1979 to 1989, Kohut also founded Princeton Survey Research Associates and later helped start the Washington-based Pew Research Center, a "fact tank" that runs independent surveys of U.S. public opinion on politics, public policy and the press.

"In an era when many numbers, including polling, have become increasingly automated and commodified, Andy always reminded us that the 'public' in public opinion is not an indiscriminate force. It is people," Pew president Michael Dimock said in a statement.

Kohut served as founding director and president of Pew from 2004 to 2012, providing regular commentary in print, radio and television and in testimony to Congress. Kohut's regular public presence led the Washington Examiner to describe him in a 2008 profile as "the man to see when polling questions arise — the public face of public opinion polling."

He was diagnosed with chronic lymphocytic leukemia in 2009. In a blog post earlier this month to honor his father's birthday, Matthew Kohut noted that his father was too ill to speak by phone. The son listed some of the important lessons his father taught him: "It's all about the question you ask" and "Don't place too much stock in credentials."

Kohut was the co-author of four books, including America Against the World. According to his son, Kohut was particularly proud of his international polling work that led to creation of Pew's Global Attitudes project, as well as surveys that closely tracked voter opinion.