Democrat Charles Bishop threw his support to Republican Bob Riley in the governor's race.
Bishop, who finished a distant second in the Democratic primary, said Riley has integrity and Gov. Siegelman has none.
A spokesman for Siegelman said Bishop's endorsement is of no consequence.
A spokesman for Riley said the congressman appreciates the support of the State Agriculture Commissioner.
Bishop polled 80,000 votes in the democratic primary on June 4. Siegelman polled more than four times that amount.
Throughout the primary campaign, Bishop questioned Siegelman's integrity.