Washington (CNN) -- Federal election monitors have been sent to 11 counties in Mississippi to ensure the voting rights of African-American primary voters, the Justice Department said Monday.

The department would not comment on the reason for these monitors. Usually monitors are sent to places where there have been allegations of discrimination in the past.

Primary elections are being held statewide Tuesday, but federal officials are being dispatched to only 11 of Mississippi's 82 counties. All but one of the counties is a majority black jurisdiction, officials said.

Republicans have a contested race for governor to replace Haley Barbour, who is term-limited. The GOP also has races for lieutenant governor, secretary of state, treasurer and agriculture commissioner.

The only Democratic statewide primary race is for governor.

Federal monitors have been dispatched to Mississippi several times since the Voting Rights Act of 1965 was passed to protect against racial discrimination at polling locations.

The observers are being sent to Bolivar, Clay, Copiah, Humphreys, Jefferson Davis, Noxubee, Panola, Quitman, Sunflower, Tallahatcchie and Wilkinson counties. Only Panola County has a majority of white voters.