? Republicans picked Kansas Treasurer Ron Estes on Thursday as their nominee for a south central Kansas congressional seat held for more than two decades by the GOP but vacated recently by Mike Pompeo, who recently became President Donald Trump’s CIA director.

The April 11 vote is the nation’s first special congressional election since Trump’s win, and Democrats are hoping to channel voter discontent into an upset in the heavily Republican district.

But GOP leaders are not taking the seat for granted.

“These special elections are low turnout, which means if a group really gets organized and energized and well funded, they can boost their own turnout — which would flip a seat. So we are not taking this as just a solid Republican seat that we will win easily,” said Clay Barker, executive director of the Kansas Republican Party.

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 state’s 4th District seat in 2010, when Tiahrt gave it up to run unsuccessfully for the U.S. Senate. Tiahrt lost a GOP primary race to Pompeo in 2014, and he was among a crowded field seeking his party’s nomination.

But after two ballot rounds, the delegates chose Estes as their standard bearer with 66 votes. Alan Cobb, a former Trump campaign staffer and ex-lobbyist for Koch Industries, trailed with 43 votes. Tiahrt garnered 17 votes. Former talk show host Joseph Ashby and lawyer George Bruce were eliminated after getting only 10 votes each in the first round of balloting.

Democrats are already mounting voter registration drives, organizing local party leaders and urging voters to elect a Democrat who will be a check on Trump in Washington, D.C.

“This special election gives people that have been so angry and frustrated with what the Trump administration has been doing since they have taken over, it gives them their first chance to fight back,” said Kerry Gooch, executive director of the Kansas Democratic Party.

Barker said he has received a call from the White House and Trump’s aides are interested in the race because it is the first since November.

Estes, who was one of the electors who voted for Trump, said he is pleased with the direction the new president has taken the country.

He told the delegates that he is running for Congress because “we need to shake up Washington,” saying the people now have the opportunity to preserve the country following a conservative vision.

The president and Congress have a lot of things to face such as repealing and replacing Obamacare and passing a balanced budget amendment, Estes told them.

Democrats and Libertarians will both choose their candidates on Saturday.