Kivuitu called for restraint during political campaigning across Kenya.
"The electoral commission calls upon all participants in the election campaign to observe peace and decorum," he said.
Vote rigging has occurred in previous polls and Kivuitu said that the national assembly has yet to empower his commission to tackle cases of electoral fraud.
"We have teeth, but we cannot bite. The commission has powers to deal with such incidents [rigging] but we do not have the power to enforce them," Kivuitu said.
Odinga was once an ally of Kibaki, but the incumbent fired him in 2005 for successfully campaigning against government-backed constitutional changes.
According to opinion polls released Friday, Odinga has 50 per cent of public support to Kibaki's 39 per cent, while Musyoka has eight per cent.
Odinga, from the Orange Democratic Movement (ODM) has pledged to devolve power to the grass roots and fight systemic graft, and comes from the western Kenya Luo tribe.
The Luo tribe has allied with the Luyha tribe against the dominant Kikuyu tribe, of which Kibaki is a member.
Kibaki, who launched a new Party of National Unity (PNU) last month, has won praise for economic policies and the introduction of free primary education, but two graft scandals, rising crime and tribal unrest have also occurred during his rule.