FILE PHOTO: Representative Kevin Cramer (R-ND) speaks at the 2018 North Dakota Republican Party Convention in Grand Forks, North Dakota, U.S., April 7, 2018. REUTERS/Dan Koeck/File Photo

(Reuters) - Republican U.S. Representative Kevin Cramer on Tuesday unseated Democratic Senator Heidi Heitkamp, who has served North Dakota in the upper chamber since 2013, helping his party’s effort to maintain control of the Senate.