(CNN) For years, Rep. Steve King of Iowa and Bob Vander Plaats, an influential Christian conservative, have fought on the same side of the culture wars, attending the same summits and bus tours to attack Republican boogeymen like Planned Parenthood and the Affordable Care Act. In 2016, they teamed up to co-chair the presidential campaign of Texas Sen. Ted Cruz, who won the Iowa caucuses after securing their support.
But last year, Vander Plaats broke that alliance by endorsing one of King's primary opponents, state senator Randy Feenstra, reflecting the recent split between GOP leaders and the nine-term congressman after racist statements he made in a New York Times interview in January 2019. House Republican Leader Kevin McCarthy stripped King of his committee assignments and the Trump administration barred him from Air Force One when the President visited Iowa last June.
A year later, King's remarks questioning how "white nationalist, white supremacist, Western civilization" became offensive continue to reverberate, undermining his bid to win the party's primary on Tuesday. The race is expected to be close, with tens of thousands of absentee ballots cast during the pandemic injecting even more uncertainty into the contest.
The primary fight is an undeniable referendum on King -- not on his conservatism, but on his effectiveness in office. His lack of power, far more than his specific words and history of remarks on race, has become a central issue in this year's race, with opponents arguing that he is unable to represent their views in the House or to the administration.
They warn that if the congressman wins the primary, he will jeopardize not only his House seat in a deep red district, but also endanger every other Republican on the ticket, including President Donald Trump and Iowa Sen. Joni Ernst.
"If you're going to be a representative, the whole part of being a representative is you got to represent the people," Vander Plaats, the president of the Family Leader, a social conservative group, told CNN. "If your voice has been taken away, then it's time to move on."
That's an argument Feenstra makes again and again.
"The 4th District needs a seat at the table -- an effective conservative voice," Feenstra said during a televised debate this week. "Our district, our President, deserve an effective conservative leader in Congress."
Feenstra is viewed as King's toughest opponent in a five-way race that includes former state legislator Jeremy Taylor, businessmen Steve Reeder and Army veteran Bret Richards. Feenstra has won marquee endorsements and financial support from conservative groups in Washington, including the Chamber of Commerce and the National Right to Life Committee. He tells voters he would like a seat on the House Agriculture Committee -- something King no longer has. And he boasts a much greater campaign war chest, reporting over $415,000 on hand at the end of March compared to less than $30,000 for King.
For his part, King argues that his words were taken out of context and mischaracterized, and he blames Republican leaders for leading a vendetta against him in Washington.
"The Never Trumpers are the people who ginned this all up," King said in a debate last week, speaking with an air of defiance about the Republicans "who want Steve King out of the way."
King, an anti-immigration hardliner, has a well-documented history of controversial statements. In 2012, he compared immigrants to dogs. In 2013, during a debate over whether to grant young people who illegally entered the country a path to citizenship, King said some potential beneficiaries have "calves the size of cantaloupes because they're hauling 75 pounds of marijuana across the desert." In 2018, King retweeted a Nazi sympathizer and later said he didn't know the person.
Vander Plaats said there's been a "growing fatigue" with King in the 4th District and a "gradual clarity" that "his voice is no longer desired at the table." Vander Plaats appears in an ad released earlier this month by the super PAC Priorities for Iowa Political Fund. The six-figure ad will be on the air in the Des Moines, Iowa, market until Tuesday, according to two sources.
King told CNN that Vander Plaats is "a hypocrite with a grudge," criticizing the Family Leader president for endorsing Feenstra even though the state senator has supported expanding gambling in the state.
"This campaign has highlighted the true nature and character of both Vander Plaats and Feenstra," King said. "There are no principles either won't sacrifice in their misguided effort to shut down real conservatives and hand this district over to RINOs and NeverTrumpers."
The congressman has also charged that Vander Plaats' endorsement is payback for when King nominated Kim Reynolds for lieutenant governor in 2010 over him.
"I think that's an excuse of not getting the endorsement versus reality," Vander Plaats told CNN. "He knows way better than that and I know way better that. And I think, more than that, the people of Iowa know way better than that."
King enjoys a number of advantages despite the controversy over his remarks, including facing multiple Republicans that will fracture the vote against him. And he is still the best-known candidate, although it's an open question whether the power of incumbency, in this case, is a positive attribute.
The congressman has sailed to reelection every two years since 2002, with the exception of a tight race in 2018 against Democrat J.D. Scholten, a former professional baseball player who is running again. The 4th Congressional District is the state's largest, in terms of geography, covering 39 of Iowa's 99 counties. It blankets much of the state's northwest quadrant, from small towns like Defiance and Dennison to mid-size cities like Fort Dodge and Sioux City.
When asked if he was concerned about losing his primary, King told CNN, "You never want to take anything for granted but I know those folks in Northwest Iowa."
The biggest uncertainty heading into Tuesday, according to Republicans strategists in Iowa, is the number of absentee ballots. For the first time, all Iowa voters were sent request forms for mail-in ballots and as of Thursday, nearly 70,000 ballots had been sent, with nearly 47,000 already returned, according to the office of Iowa Secretary of State Paul Pate.
Two years ago, fewer than 3,000 absentee ballots were recorded. But with Iowa still recovering from its coronavirus crisis, including many hotspots in meatpacking towns across the district, it's unknown whether a dramatic uptick in absentee ballots means more voters are paying attention or whether a similar number just intend to vote from the safety of their homes.
"I think it's both," said Brett Barker, a Republican party chairman for Story County, which encompasses Ames, Iowa. "I think there's interest and enthusiasm, and I also think the Secretary of State made it easy for voters to vote absentee."
President Donald Trump is also a wild card. He has yet to weigh in on the primary, even though he voiced support for other Iowa Republicans in recent days. One White House adviser told CNN there were no plans for the President to weigh in but that always remained his choice.
Yet even King's Republican opponents may welcome him back into the fold if he wins.
Vander Plaats told CNN that he would "see myself supporting Steve King over J.D. Scholten."
"I think If Congressman King were to emerge the victor in the primary, I really hope and sincerely pray, that this was a wake up call for him," Vander Plaats said. "It's time to move forward with diligence and leadership."
But Vander Plaats said that if King does win the primary, he fears a Scholten win in November, adding that the congressman's campaign would be a "drag" on the Republican ticket, hurting Ernst and Trump's reelection races.
"This goes even beyond Congressman King," Vander Plaats said. "If there's a fatigue in wanting to vote for your Congressman, everybody that's on the ballot with him is at risk."