Kansas's 4th congressional district is located in the south-center region of the state, centering on the city of Wichita and Sedgwick County, which contain approximately two-thirds of the district's voters. Sixteen other counties make up the rest of the district, including Barber, Butler, Chautauqua, Comanche, Cowley, Edwards, Elk, Greenwood, Harper, Harvey, Kingman, Kiowa, Pratt, Stafford, and Sumner counties, as well as a portion of southwestern Pawnee County. Regarded as a conservative district, the seat is considered to be safe for Republicans; the Fourth District had a Cook Partisan Voting Index of R+15 following the 2016 presidential election. Going into the election, the seat had not been held by a Democrat in more than twenty years, since Dan Glickman lost his reelection campaign in the 1994 midterms. At the time of the special election, the Republican Party held about a 2-to-1 advantage in voter registration in the district, with 186,850 registered Republicans to 95,788 registered Democrats. Republican Donald Trump won the district by a 27-point margin in the 2016 presidential election, receiving 60% of the vote to Democrat Hillary Clinton's 33%. Republican Mitt Romney defeated Democrat Barack Obama by a similar 26-point margin in 2012, taking approximately 62% of the vote to Obama's 36%.
Election
On January 23, 2017, the U.S. Representative for Kansas's 4th congressional district, Mike Pompeo, resigned after being nominated by President Donald Trump as Director of the Central Intelligence Agency. He was confirmed by the United States Senate. Gov. Sam Brownback had five days to declare a special election to be held between 45 and 60 days after being called. The day following Pompeo's resignation, Brownback declared a special election to take place on April 11. Nominees for each party were selected by a district convention of party activists. Independent candidates were eligible to gain ballot access upon submitting 3,000 signatures within the first 25 days after the election was called. Although not initially expecting a close race, the National Republican Congressional Committee spent $100,000 on advertising in the last week of the campaign, and Republican luminaries such as Sen. Ted Cruz of Texas, President Donald Trump, and Vice President Mike Pence recorded robocalls or campaigned in person supporting their nominee Ron Estes. On April 10, the Cook Political Report moved the rating of the district to Lean Republican. Estes won the election by 6.2% over political newcomer James Thompson. This not only marked a dramatic shift from the 61.6%–29.6% margin that Pompeo had been re-elected by in the previous year's regularly-scheduled election, but this was also the closest race in the district since incumbent Todd Tiahrt, who held the seat from 1995 to 2011, edged out Democrat Randy Rathburn by 3% in 1996.
The Associated Press called the election for Estes while he was leading by 6% with 88% of precincts reporting. The lead was 6.2% when all the votes were tallied.
