Brownback to call a special election, set for April 11, 2017, to fill Pompeo's vacated Congressional seat. 2016 regular election In the 2016 national elections, the district's Republican nominees for President (Trump) and Congressman (Pompeo) overwhelmingly defeated the Democratic nominees (Clinton and Giroux), by two-to-one margins in the 4th district. (as happened with Pompeo's previous Democratic challengers). 2017 special election Kansas Governor Sam Brownback, acting on his authority, announced a special election would be held on April 11, 2017, to fill the vacancy left by Rep. Pompeo's resignation. Republican, Democratic, and Libertarian parties would select their nominees through district caucuses, run by the respective party organizations, voting through delegates selected by their respective party rules. It would be the first Congressional election since the 2016 national election, and thus drew national attention. Republicans nominated Kansas State Treasurer Ron Estes. Democrats nominated civil-rights attorney James Thompson, a political novice. Libertarians nominated aviation instructor Chris Rockhold, also a political novice. Initial assumptions were that this election's outcome was a foregone conclusion: The Republican would win overwhelmingly again. However, Democratic nominee Thompson, aided with numerous energetic supporters (particularly former local campaigners for Bernie Sanders, who had taken the 2016 Kansas Democratic Presidential Caucus by 75%), began to show signs of the first serious fourth district challenge to Republicans since Glickman's loss a quarter-century earlier. The Thompson campaign raised about $254,000 by the final campaign finance-reporting deadline, and over 97% was from individual donors—with a last-minute infusion of only $10,000 from the state party, reflecting a lack of support from his state party and national organizations. By comparison, Estes raised about $318,000—plus another $94,000 from the National Republican Congressional Committee (NRCC) after the filing deadline—largely from outside groups and big (over $1,000) donors. The Thompson campaign emphasized Thompson's working class progressive credentials, telling the story of his childhood poverty and use of education as a ladder to opportunity. Another a key focus was his status as a U.S. Army veteran and advocacy for Second Amendment rights, featuring images of him firing his assault rifle. The campaign strongly emphasized his desire to defend the Constitution, inferring a reference to President Trump. The Thompson campaign attempted to focus public attention on Estes' close connections to exceptionally unpopular Governor Sam Brownback. In response, Estes and the Republican party simply branded Thompson as "too liberal for Kansas." Estes' low-key campaign included refusing to attend several debates with Thompson