A member of the National Action Party (Partido Acción Nacional, PAN), he served as a federal deputy and, between 2 December 2006 and 2 March 2009, director of the Mexican Social Security Institute.
He attained a master's degree in political science from El Colegio de México and became a PhD candidate in the same field at the University of California, San Diego, United States.
Among his publications in academic journals are Counting the Number of Parties: An Alternative Index, published in the American Political Science Review, as well as Schools of interpretation of the Mexican political system, 1988 Elections in Mexico: the crisis of authoritarianism, written with Jeffrey Weldon, and Electoral Processes in Mexico, written with Alvaro Arreola Ayala and published in the Revista Mexicana de Sociología.
He shared duties with other directors like Alonso Lujambio, Maurice Murphy, Jacqueline Peschard, Emilio Zebadua and the Executive President, José Woldenberg.
Although the Federal District Legislative Assembly decriminalized abortion in Mexico City in the first twelve weeks of gestation, Molinar declined to provide that service in the clinics of the institute he headed.