(CNN) - New Jersey Gov. Chris Christie opted for a special election to fill a newly vacant Senate seat through 2014 instead of appointing a replacement through that time, saying the decision was about giving voters "a choice and a voice in the process" and was not driven by political self-interest.

While the Republican's decision for a special October ballot could help him avoid stronger Democratic turnout in his re-election bid a month later, it also opens him up to criticism from his own party that is on the short end of the balance of power in the Senate.