James M. Burns, a Scholar of Presidents and Leadership

James MacGregor Burns, a Pulitzer Prize-winning biographer and political scientist who wrote voluminously about the nature of leadership in general and the presidency in particular, died on Tuesday at his home in Williamstown, Mass. He was 95. The historian Michael Beschloss, a friend and former student, confirmed the death.

Mr. Burns, who taught at Williams College for most of the last half of the 20th century, was the author of more than 20 books, most notably “Roosevelt: Soldier of Freedom” (1970), a major study of President Franklin D. Roosevelt’s stewardship of the country through World War II. It was awarded both the Pulitzer Prize and the National Book Award.

An informal adviser to presidents, Mr. Burns was a liberal Democrat who once ran for Congress from the westernmost district of Massachusetts. Though he sometimes wrote prescriptively from — or for — the left, over all he managed the neat trick of neither hiding his political viewpoint in his work nor funneling his work through it. His work was often critical of American government and its system of checks and balances, which in his view was an obstacle to visionary progress, particularly as a rein on the presidency. In works like “The Deadlock of Democracy” (1963) and “Packing the Court: The Rise of Judicial Power and the Coming Crisis of the Supreme Court” (2009), he argued for systemic changes, calling for a population-based Senate, term limits for Supreme Court justices and an end to midterm elections.

In 1978, after a half-dozen more books, including the second Roosevelt volume and separate studies of the presidency and of state and local governments, Mr. Burns wrote “Leadership,” an amalgamation of a lifetime of thinking about the qualities shared and exemplified by world leaders throughout history. It became a standard academic text in the emerging discipline known as leadership studies, and Mr. Burns’s concept of transforming leadership itself became the subject of hundreds of doctoral theses.

Asked to describe Mr. Burns’s passions away from his writing, Ms. Sorenson named skiing, his two golden retrievers, Jefferson and Roosevelt, the blueberry patch in his yard and his students.

“He would never bump a student appointment to meet with someone more important,” Ms. Sorenson said. “I remember Hillary Clinton once inviting him to tea, and he wouldn’t go because he had to meet with a student. And he would never leave his place in Williamstown during blueberry season.”