King, 63, is a favorite of hardline conservatives. He was first elected to Congress in 2002 and most recently re-elected in 2012, narrowly defeating former Iowa First Lady Christie Vilsack. King currently represents Iowa's 4th district, which includes Sioux City and Ames.
PHOTO: ALEX BRANDON / ASSOCIATED PRESS
Reynolds, 53, is the current lieutenant governor of Iowa. Gov. Terry Branstad has already stated he is uninterested in seeking the vacant Senate seat.
PHOTO: CHARLIE NEIBERGALL / AP PHOTO
Northey, 53, has served as Iowa's secretary of agriculture since January 2007. Northey's name has been floated for the vacant Senate seat, but he's made no official announcement concerning his potential candidacy.
PHOTO: KENT SIEVERS / THE WORLD-HERALD
Braley, 55, represents the northeastern portion of Iowa that includes Cedar Rapids. First elected to Congress in 2006, Braley is considered the race's leading candidate, according to a report issued by Public Policy Polling. In the poll, respondents favored Braley in a potential general election against King, Latham, Reynolds and Bob Vander Plaats, a former Iowa gubernatorial candidate and CEO of The Family Leader.
PHOTO: MIKE BURLEY / THE TELEGRAPH HERALD