In 2005, one year into her job as San Francisco district attorney, Kamala Harris was showing a new hire around the office.

Ms. Harris had recruited Lateefah Simon, a 28-year-old racial justice activist, to lead a new program aimed at keeping first-time drug offenders out of jail. As the two women walked the halls, they stopped in front of a wall lined with photographs of Ms. Harris’s predecessors — all of them white men.

“The expectation of our community is that I’m going to fix all the havoc,” Ms. Harris said, according to Ms. Simon’s recollection. “They’re going to want me to fix all the racism, all the dysfunction, in the next four years.”

But in reality, Ms. Harris said, change will happen “bit by bit.”

The comment underscored the political philosophy that has guided Ms. Harris’s style of governance for decades. It is among the more striking contradictions of Ms. Harris’s candidacy: While she would bring about historic change if elected, as the first woman, the first Asian American and the second Black person to be hold the office, she is not offering sweeping change in policy. She is at heart an institutionalist, defined by a deliberate style, focused on granular impacts over broad society shifts.

It’s an approach that diverges from those of previous leaders who have captured the imaginations of the Democratic Party. President Barack Obama presented Americans with a hopeful vision that promised to heal some of the nation’s deepest racial, geographic and partisan divides. Senator Bernie Sanders of Vermont electrified Democrats with his populist calls for structural change and major economic reform. And President Biden promised to “restore the soul” of a nation fractured by the chaos of his predecessor’s administration.

Ms. Harris is a leader who rejects political labels. She believes in crafting clear rules and in step-by-step change that can add up to durable transformation in American society.