"I know for certain that Chris would not have wanted his name or memory used in that connection," Mary Commanday wrote in the letter
, which was published Saturday. "I hope that there will be an immediate and permanent stop to this opportunistic and cynical use by the campaign."
The Benghazi attacks
were frequently mentioned in speeches at this week's Republican National Convention in Cleveland, where speakers used it as a reason presumptive Democratic nominee Hillary Clinton is unfit for the presidency.
Clinton was secretary of state at the time of the attacks. Some conservatives blame Clinton
and the Obama administration for security failures in Benghazi that they blame for the deaths of Stevens and three other Americans.
At one point during the convention, another victim's mother, Pat Smith, spoke before the audience and blamed Clinton for the death of her son
, IT expert Sean Smith.