By DEVLIN BARRETT, Associated Press Writer

Sen. Hillary Clinton referred Friday to the assassination of Robert Kennedy in 1968 Democratic campaign as a reason she should continue to campaign despite increasingly long odds.

Clinton was responding to a question from the Sioux Falls Argus Leader editorial board about calls for her to drop out of the race.

"My husband did not wrap up the nomination in 1992 until he won the California primary somewhere in the middle of June, right? We all remember Bobby Kennedy was assassinated in June in California. I don't understand it," she said, dismissing the idea of dropping out.

Clinton said she didn't understand why, given this history, some Democrats were calling for her to quit.

Her remark about an assassination during a primary campaign drew a quick response from rival Barack Obama's campaign.

"Sen. Clinton's statement before the Argus Leader editorial board was unfortunate and has no place in this campaign," said Obama spokesman Bill Burton.

Clinton spokesman Mo Elleithee said the senator was only referring to her husband and Kennedy "as historical examples of the nominating process going well into the summer and any reading into it beyond that would be inaccurate."