WASHINGTON  Representative James E. Clyburn of South Carolina, the highest-ranking African-American in Congress, said he was rethinking his neutral stance in his state’s presidential primary out of disappointment at comments by Bill and Hillary Rodham Clinton that he saw as diminishing the historic role of civil rights activists.

Mr. Clyburn, a veteran of the civil rights movement and a power in state Democratic politics, put himself on the sidelines more than a year ago to help secure an early primary for South Carolina, saying he wanted to encourage all candidates to take part. But he said recent remarks by the Clintons that he saw as distorting civil rights history could change his mind.

“We have to be very, very careful about how we speak about that era in American politics,” said Mr. Clyburn, who was shaped by his searing experiences as a youth in the segregated South and his own activism in those days. “It is one thing to run a campaign and be respectful of everyone’s motives and actions, and it is something else to denigrate those. That bothered me a great deal.”

In an interview with Fox News on Monday, Mrs. Clinton, who was locked in a running exchange with Senator Barack Obama, a rival for the Democratic presidential nomination, over the meaning of the legacies of President John F. Kennedy and the Rev. Dr. Martin Luther King Jr., tried to make a point about presidential leadership.