Baltimore Circuit Judge Emanuel Brown also ordered Henson, 63, to complete 300 hours of community service. Brown announced his sentence after listening to Henson cast himself as a victim in his final remarks to the court.
While Brown did not comment on Henson's remarks, the chief prosecutor said later that the consultant's comments underscored a belief that he would return to dirty tricks in the future.
"There was the implication that he would do it again," said Maryland State Prosecutor Emmet C. Davitt.
A jury found Henson guilty last month of conspiracy to violate election law by withholding an authority line for the call, but acquitted him of three other counts, including election fraud. Henson has acknowledged that his campaign consulting company recorded the automated call, which told registered Democrats in Baltimore andPrince George's County to "relax" and stay home.
The call implied that Gov.Martin O'Malley, a Democrat, had already won his race against Republican former Gov.Robert L. Ehrlich Jr.even though the polls were still open. Prosecutors said it was intended to trick black voters into staying home. The Ehrlich campaign paid Henson $16,000 a month — for a total of $112,000 — for his work as a consultant.
Henson's sentencing stood in contrast to the punishment handed out to Ehrlich campaign manager Paul Schurick, who was convicted of four counts, including election fraud, but was not sentenced to jail. Schurick was ordered to serve 30 days of home detention and 500 hours of community service. Schurick's case was heard by Baltimore Circuit Judge Lawrence P. Fletcher-Hill.
In a separate federal civil case last month, Henson was ordered to pay a $1 million fine for violating the Telephone Consumer Protection Act. That lawsuit was filed by the Maryland attorney general's office.
Edward Smith Jr., Henson's attorney, who had earlier said men in "smoke-filled rooms" were behind the criminal prosecution, objected to Brown's sentence.
"This is particularly harsh treatment," he said, asking the judge to reconsider. He also asked that Henson be allowed to begin his sentence at a later date while he appeals the jury's verdict. Brown said no.
The judge said the sentencing was designed to send a message. "There seems to be a culture that says anything goes in politics from time to time," he said. "That culture must change."
Prosecutors said they initially were not going to ask for jail time for Henson, but then saw a televised interview in which he refused to accept blame for his actions.
"Mr. Henson, unlike most political consultants who act with some degree of integrity, is in the business of providing a face for campaigns to hide behind when they want to do what's reprehensible, what's sleazy, and don't want to have to put their names behind it," said Deputy State Prosecutor Thomas M. McDonough.
McDonough pointed out that Schurick handled his day of sentencing very differently.
"Mr. Schurick clearly took responsibility at sentencing for his actions and expressed extreme remorse," he said. "Mr. Henson blamed the governor for his situation. He blamed the Democratic hierarchy for his situation, and he suggested his African-American ancestry is the sole reason he's in this position."
McDonough called Henson a "continued danger to the integrity of the political process."
During his remarks, Henson told the court his case showed that "there's certainly a lot wrong with the judicial process."
"What has occurred his not been fair," he said. "This has not been justice."
The robocall, which went out to 112,000 households in heavily Democratic Baltimore and Prince George's County two hours before polls closed, said O'Malley and President Barack Obama had been successful and suggested voters could stay home. Obama wasn't on the ballot that year. Ehrlich has said he knew nothing of the call.
Maryland Democratic Party Chair Yvette Lewis said in a statement that the outcomes of Henson and Schurick's trials "sent a loud and clear message" that "voter suppression will not be tolerated."
"While these decisions are a victory for the voters of Maryland, I remain concerned about Republican efforts across the country to make voting more difficult," Lewis said.
Both Henson and Schurick had previously worked for Democrats. Henson's career has been especially colorful while working for Democratic Party campaigns.
In 1998, Henson disseminated campaign literature on behalf of then-Gov. Parris Glendening that critics characterized as race-baiting. He paid a crowd to shout down the late Del. Howard "Pete" Rawlings when he endorsed then-mayoral candidate O'Malley in 1999. And he called Ehrlich, his future client, a Nazi while working for the Kathleen Kennedy Townsend campaign in 2002.