Democrats are hoping to channel voter discontent into an upset as they pick their nominee Saturday for a south central Kansas congressional seat held for more than two decades by Republicans, but vacated when Mike Pompeo became President Donald Trump’s CIA director.

A special election April 11 will decide Pompeo’s replacement, the nation’s first special congressional election since Trump took office. Democrats view it as their best chance to flip a seat in a heavily Republican district.

Republicans have represented the district that encompasses the state’s largest city of Wichita since Todd Tiahrt unseated veteran Democratic Rep. Dan Glickman in 1994. Pompeo won the 4th District seat in 2010, when Tiahrt gave it up to run unsuccessfully for the U.S. Senate.