Sander Vanocur, the television newsman who became familiar to American viewers as a prominent White House correspondent during the Kennedy administration and as a tough questioner in presidential debates, died on Monday night in a hospice facility in Santa Barbara, Calif. He was 91.

His son Christopher said the cause was complications of dementia. Mr. Vanocur lived nearby in Montecito.

Mr. Vanocur (pronounced van-OH-kur) was the last surviving journalist of the four who, as a panel, questioned Senator John F. Kennedy and Vice President Richard M. Nixon in America’s first televised presidential debate, on Sept. 26, 1960. (The others were Robert H. Fleming of ABC, Stuart Novins of CBS and Charles Warren of Mutual Broadcasting. Howard K. Smith, then of CBS, was the moderator.)

In a memorable moment, Mr. Vanocur asked Nixon about a damaging remark that President Dwight D. Eisenhower had made about his vice president — that he could not remember a single idea of Nixon’s that was adopted.