The United States Senate Elections were held on November 2nd, 2010. 34 seats from Class 3 were up for election along with 2 vacancies both from Class 1. Of the 36 senate seats up, Democrats and Republicans were each defending 18 seats. For the Democrats, 13 incumbents were running with 3 retirements and 2 vacancies, while for the Republicans, 12 incumbents were running with 6 retirements.