<P> Mitch McConnell Republican </P> <P> Elections to the United States Senate were a part of the elections held in the United States on November 4, 2014 (and in some areas for a period of time ending November 4, 2014). 33 Class 2 seats in the 100 - member United States Senate were up for election, in addition to three Class 3 seats due to expire on January 3, 2017 . The candidates winning the regular elections will serve six - year terms from January 3, 2015 to January 3, 2021 . The elections marked 100 years of direct elections of U.S. Senators . Twenty - one of the open seats were held by the Democratic Party, while fifteen were held by the Republican Party . </P> <P> The Republicans regained the majority of the Senate in the 114th Congress, which started in January 2015; the Republicans had not controlled the Senate since January 2007 . They had needed a net gain of at least six seats to obtain a majority . They successfully held all of their seats, and gained nine Democratic - held seats . Republicans defeated five Democratic incumbents: </P> <Ul> <Li> Mark Begich of Alaska lost to Dan Sullivan </Li> <Li> Mark Pryor of Arkansas lost to Tom Cotton </Li> <Li> Mark Udall of Colorado lost to Cory Gardner </Li> <Li> Mary Landrieu of Louisiana lost to Bill Cassidy </Li> <Li> Kay Hagan of North Carolina lost to Thom Tillis </Li> </Ul>

When did republicans gain control of the senate