Estes was expected to rom in a district that President Trump carried by 27 points, But Thompson came surprisingly close, losing by less than seven points.
Republicans have held the 4th District seat for more than two decades. Ted Cruz who came to Wichita to campaign for Estes the day before a special election at Yingling Aviation, Monday, April 10, 2017, in Wichita, Kan. Jim Thompson was running in what's a pretty hard district for a Democrat and nearly pulled off an upset.
GOP strategists warned in recent days that Democrat James Thompson, a civil rights attorney, was in striking distance against Estes, Kansas state treasurer from Wichita, in the special election to replace Mike Pompeo.
Estes received 53 percent of the vote in Kansas's 4th Congressional District, compared to Thompson's 46 percent.
Tuesday's vote was in a heavily Republican district where Trump won 60 percent of votes in November's election. Estes won 52.5 percent of the vote while Thompson took 45.7 percent of the vote.
According to Bob Beatty, a political scientist at Washburn University, the results should make Republicans extremely anxious.
The second highest spender was Republican candidate Dan Moody, who spent $2 million in ads districtwide. Others are in Georgia, Montana, and SC. Georgia's 6th District seat is vacant because Republican Tom Price stepped down to be Trump's secretary of Health and Human Services.
Because of Brownback, it's hard to say how much Estes' narrow victory can be seen as a referendum on Trump's presidency.
While the Kansas result suggested some blowback against Trump, another important factor was anger with the state's unpopular Republican governor Sam Brownback. Democrats will tap into the deep well of voter frustration after the governor made Kansas a veritable laboratory for a number of broad tax cuts that left the state with minimal revenues, leading to a budget crisis.
Lucy Jones-Phillips, a 31-year-old insurance representative and Democrat, acknowledged she doesn't vote in every election, but said she voted for Thompson because she wanted to register her disappointment in Brownback, especially his veto of an expansion of Medicaid.
As Thompson and Estes battled it out in the final days before the special election, the national Democratic Party did little to counter the late effort of Republican leaders, who poured money into the congressional campaign. Republicans pulled in U.S. Sen. Both Trump and Vice President Mike Pence recorded robocalls for him, and Texas Sen. A June 20 runoff looms if no candidate gets a majority vote, but Ossoff is aiming for an outright win and is hovering in the mid-40s in recent polling.
But there were 150,000 more votes cast in the district in 2016 than this special election.
The 2nd District covers most of eastern Kansas outside the Kansas City metropolitan area.
The unofficial results were reported by the 17 county election officers in the 4th District on election night. But early voting this month favored Democrats, 44.5 to 43.5 percent, and Estes ultimately squeezed by with a far smaller margin than the president's.
Edwards County: Estes, 479 (78 percent); Thompson, 129 (21 percent); Rockhold 8 (1 percent).
But Lake said the Kansas race shows more broadly how Republicans running textbook campaigns in seemingly safe districts have good reason to be antsy. "And we're going to make sure we change things in Washington".
After Pompeo resigned his seat to run the Central Intelligence Agency, neither capitalist party assigned much importance to the contest to fill the vacancy in a district that Trump carried by a margin of 27 percent, and Pompeo won by an even wider margin.