Rep. Steve King of Iowa, a divisive Republican who has embraced ethnic nationalism, survived a challenge in November from J.D. Scholten, a paralegal and former baseball player, by about 10,000 votes.

But in 2020, King will have to defend his seat in a deep-red swath of northwestern Iowa not against a Democrat and first-time candidate but against a fellow Republican, Randy Feenstra, who has served in the Iowa Senate since 2009. He is now the assistant majority leader and chairman of the Ways and Means Committee.

Feenstra, 49, of Hull, said Wednesday that he would take on the nine-term congressman, whose racially incendiary rhetoric and association with far-right movements in Europe and Canada have been widely rebuked, even by some within his party. The House Republican campaign arm said last fall that it would stay away from his district, as the group’s chairman, Rep. Steve Stivers (R-Ohio), censured his colleague on Twitter for “white supremacy and hate."

King, 69, has dismissed the criticism, which intensified ahead of the midterm elections but drew on controversies stretching back several years.

The congressman declared on Twitter in 2017: “We can’t restore our civilization with somebody else’s babies.” In June, he retweeted a message from a self-described “Nazi sympathizer.” In the fall, he voiced support for Faith Goldy, an unsuccessful Toronto mayoral candidate who has promoted the baseless notion that a “white genocide” is underway. Shortly thereafter, reports surfaced that King had met in August with members of an Austrian political party founded by former Nazis, during a trip funded by a group that promotes awareness of the Holocaust.

Antipathy toward the congressman, whose ideas have nonetheless moved closer to the mainstream in President Trump’s GOP, grew after a massacre at a Pittsburgh synagogue in October. At a town hall meeting, King became incensed when an attendee asked him whether his views on race and identity resembled those of Robert Bowers, the man accused of gunning down 11 Jewish congregants.

Feenstra, in announcing his plans, didn’t enumerate these controversies, or even mention King by name. But his message was clear.

“Today, Iowa’s 4th District doesn’t have a voice in Washington, because our current representative’s caustic nature has left us without a seat at the table,” he said in a statement to local media. “We don’t need any more sideshows or distractions, we need to start winning for Iowa’s families.”

The choice to echo a promise made by Trump — “We’re going to win so much. You’re going to get tired of winning,” the president once said — was telling. Feenstra is hardly running to the left of King, one of Trump’s most devoted congressional acolytes. The state senator pitched himself as better positioned to advance the White House’s agenda, a message brought home by his criticism of House Democrats.

“What we’ve seen this past week from the new Democratic majority in Congress is appalling,” the state senator said, in an apparent reference to Democrats' refusal to fund Trump’s border wall, which has led to an impasse in negotiations over the partial government shutdown.

Feenstra’s inaugural tweets on Wednesday suggested that he could outdo King in advancing Trump’s agenda — by flying under the radar.

King hasn’t said publicly whether he will seek reelection in 2020. But the congressman’s staff, not known for shying away from a fight, wasted no time in attacking Feenstra.

In an email to the Des Moines Register, Jeff King, the congressman’s son and spokesman, claimed that the state senator had previously promised the incumbent that he “would never” run against him. Feenstra didn’t return an email from The Washington Post late Wednesday asking him to elaborate on his plans.

The statement from the younger King went on to paint Feenstra as a puppet of the congressman’s left-wing critics.

“Today, misguided political opportunism, fueled by establishment puppeteers, has revealed that Mr. Feenstra is easily swayed by the lies of the left,” it stated, adding that the GOP challenger “offers Republican voters nothing but warmed over talking points from liberal blogs and failed Democratic candidates.”

In a further indication that in a race between the two men, they would vie to display purer loyalties to the president, the statement recalled Trump’s endorsement of King as “the world’s most conservative human being.”

This identity has helped King, who is now the lone Republican in Iowa’s House delegation, fend off previous primary challengers.

His recent opponents have not been particularly threatening. Cyndi Hanson, an educator who challenged King in the 2018 primary, was the first to admit that she was an “underdog with little name recognition,” as the Sioux City Journal reported. In 2016, King handily defeated Rick Bertrand, a Republican state senator whose attack on the incumbent as ineffective and out of touch failed to get enough voters to split with him.

Feenstra’s bid may depend on whether Iowa voters have grown weary of his combative identity as politics have further fractured over the last four years. The state’s Republican governor, for her part, has said she won’t endorse him this time around.

“The last election was a wake-up call for it to be that close,” Gov. Kim Reynolds said in an interview with an NBC affiliate in Des Moines. “That indicates that it does open the door for other individuals to take a look at that.”