J. D. Scholten, a Democrat who nearly toppled Representative Steve King of Iowa in a heavily Republican district in 2018, announced on Monday that he would run again for the seat in 2020. His decision sets up a possible rematch with Mr. King, whose history of racist remarks has made him a pariah among Republican leaders, though not always with voters.
“Last time, we were hoping to win,” Mr. Scholten said in an interview before the announcement. “Now, we are expecting to win. We know how to do it.”
Mr. King was stripped of his congressional committee assignments this year by House Republicans, after he questioned why white nationalism was offensive. He later said he had nothing to apologize for and would run in 2020 for a 10th term in his deeply conservative district in northwest Iowa.
If he survives a primary challenge next year, Mr. King will appear on the same ballot as President Trump, whose nativism and anti-immigrant remarks Mr. King long foreshadowed. In Mr. King’s Fourth District, which Mr. Trump won by nearly 30 points, voters in the past have either agreed with or overlooked Mr. King’s divisive language about Latino migrants, who sustain much of the agricultural economy there.
“Having Steve King have a voice in Congress, I think that’s at the root of why I feel it’s so important to get him out of office,” Mr. Scholten said.
Mr. Scholten, a former minor league baseball player and a fifth-generation Iowan, said he would once again crisscross the 39 counties of the largely rural district in an R.V., overnighting in Walmart parking lots, while engaging with voters about health care, agriculture and getting corporate money out of politics.
Mr. Scholten, 39, weighed running against Senator Joni Ernst, a potentially vulnerable Republican, but learned in June that national Democrats, including Senator Chuck Schumer, the minority leader, were backing a different challenger, Theresa Greenfield.
“Ultimately, I would have a tough time abandoning what we were able to accomplish and watch Steve King get re-elected if I were to run in that race,” Mr. Scholten said over the weekend. “And, I mean, the Fourth District is where my heart’s at.”
Iowa will be in the political spotlight next year, not just for its presidential caucuses in February, but also because it will feature competitive races up and down the ballot in November, for the Senate and all four of its congressional seats.
To win re-election, Mr. King must first defeat three primary challengers, most prominently Randy Feenstra, a state senator who has outraised him with the support of the Republican establishment. Mr. King brought in just $91,000 in the quarter ending in June, compared with Mr. Feenstra’s $140,000.
Money, however, has never mattered much in Mr. King’s re-elections. He has nearly universal name recognition in his district, and, until recently, voters broadly embraced his pugnacious personality and positions on bedrock conservative issues like abortion and gun rights.
Mr. Scholten, who outspent Mr. King nearly four to one in 2018, came within three percentage points of unseating him after the congressman endorsed a candidate for Toronto mayor with neo-Nazi ties and, in an interview with an Austrian publication that surfaced late in the race, seemed to endorse the “Great Replacement,” a conspiracy theory espoused by white supremacists.
In January, in an interview with The New York Times, Mr. King said, “White nationalist, white supremacist, Western civilization — how did that language become offensive?”
House Republican leaders removed him from the Judiciary and Agriculture Committees, while Mr. King defended himself by saying his remarks had been taken out of context.
Many Democratic politicians issued fresh condemnations of white nationalism over the weekend after at least 29 people were killed in mass shootings in El Paso and Dayton, Ohio, and some placed a portion of the blame on Mr. Trump’s remarks. The authorities said they were investigating the El Paso shooting as a possible hate crime.
“Words have consequences,” Mr. Scholten said when asked about the shootings. “The hatred and racism that has become too commonplace in our country does fuel violence.”
Despite his yearslong history of racist remarks, Mr. King was rebuked by Republican leaders only recently. Senator Ernst denounced Mr. King this year, but she has campaigned with him in the past, eager for the support of his voters in the state’s most conservative region.
Should Mr. Feenstra or one of the other primary challengers emerge as the nominee, Republicans would quite likely have an easier time against Mr. Scholten without Mr. King’s baggage.
If Mr. King wins the nomination, Mr. Scholten would have to win the votes of many Republicans and unaffiliated voters to defeat the congressman in a district where active registered Republicans greatly outnumber Democrats. Mr. Scholten lost to Mr. King by about 10,000 votes last year, out of 313,000 cast.
“We got 24,000 more votes last time than there are Democrats in the district,” Mr. Scholten said. “I have to do even better than that this time.”
Strategists for both parties in Iowa said they would still consider Mr. King the favorite if he became the nominee.
“Republicans in the Fourth District have not yet indicated they’ve had enough” of Mr. King, said Kurt Meyer, a Democratic county chairman in the First District. “If a Democratic candidate for president runs strong in Iowa, there’s maybe a one-in-three chance we take him out.”