James Tobin, 45, was found guilty in December of harassment by telephone.
Prosecutors said he helped arrange more than 800 hang-up calls that jammed get-out-the-vote phone lines set up by the state Democratic Party and the Manchester firefighters' union for about an hour. Republican John Sununu defeated then-Gov. Jeanne Shaheen for the Senate that day in what had been considered a cliffhanger.
At the time, Tobin was a regional official with the RNC and the National Republican Senatorial Committee, overseeing Senate campaigns in several states, including New Hampshire and Maine.
He later became New England chairman of President George W. Bush's 2004 re-election campaign, but stepped down when Democrats accused him of playing a role in the jamming.
In addition to the prison sentence, he received a $10,000 fine and two years of probation.