WASHINGTON — Republicans tried to take away Rep. Steve King's platform — but he just won't stop talking.

The Iowa congressman, already stripped of his committee assignments by the House GOP for comments about white supremacy, drew calls for his ouster from Congress by prominent members of both parties Wednesday after he said rape and incest have been essential to the propagation of humanity.

"What if we went back through all the family trees and just pulled those people out that were products of rape and incest? Would there be any population of the world left if we did that?" King said in remarks supporting abortion bans that do not make exceptions for cases of rape and incest, according to video posted online by The Des Moines Register.

Though most Republican officials have raced to distance themselves from King in recent years, his rationale for the anti-abortion case could cause broader trouble for the GOP for three reasons: he's been a favorite of President Donald Trump; the policy he was espousing is both unpopular and part of the Republican platform; and his wording may remind voters of the way 2012 Senate Republican nominees talked about "legitimate" rape and what "God intended" in the context of similar legislation.

"If Steve King actually cares about the conservative movement, he would resign from Congress today because by staying in there he’s setting the very causes and movement he cares about back by about a decade," said a Republican strategist with deep ties to the conservative movement.

This strategist, like other Republicans who spoke to NBC, said they weren't sure how far the fallout from King's latest comments would land outside his 4th District, where he won re-election by about 3 percentage points in 2018 and faces both primary challengers and a possible re-match with Democrat J.D. Scholten in 2020.

"He’s already been stripped of committee, he’s not raising any money. What’s next is kind of unclear to me," said Doug Heye, a former House GOP leadership aide. "It’s just another example of Steve King saying something truly reprehensible."

For Democrats, King represents an opportunity to tell voters — particularly suburban women — that Republicans are pushing extreme policies based on outlandish ideology.

Several Democratic presidential candidates condemned King's comments, including Sen. Kirsten Gillibrand, D-N.Y., who tweeted: “You are a disgrace. Resign."

Some Republicans say privately that Democrats should be careful what they wish for — that King is easy pickings at this point, while Randy Feenstra, an Iowa state senator who is challenging King in the 2020 GOP primary, could be harder to beat. That may be true. But, because Democratic calls for King's resignation are likely to have the effect of rallying his supporters, a desire among Republicans to quiet those calls suggests how badly the GOP wants him to go away.

Rep. Liz Cheney of Wyoming, the House Republican Conference chair, said on Twitter that King's comments were "appalling and bizarre" and she reiterated an earlier request for him to resign.

While King's take on the justification for an all-out abortion ban is an outlier in the GOP, it does bring attention to a portion of the party's platform that is not popular with the American public. Most Americans — 63 percent of those polled — say they favor keeping abortion legal in cases of rape and incest, according to a recent survey by PBS NewsHour, NPR and Marist. When the life of the mother is in danger, the number jumps to 86 percent.

Anti-abortion Republicans have been willing to promote their position against the majority opinion, but they may not want to get tangled up in a debate over King's unique way of describing it. If past is prologue, that would be particularly politically perilous.

In 2011, House Republican leaders were embarrassed when they had to rewrite an anti-abortion bill because it included language making a distinction between "forcible rape" and "rape." Many prominent members of the party had co-sponsored the original version of the bill, apparently without realizing the phrase had been written into the bill.

The following year, then-Rep. Todd Akin, R-Mo., who was then running for the Senate, explained his thinking on why rape victims should not have access to abortions in this way: "If it's a legitimate rape, the female body has ways to try to shut the whole thing down."

Richard Mourdock, an Indiana Senate candidate, later said pregnancies resulting from rape were "something God intended." Like Akin, he lost.

The other nagging issue for Republicans as the campaign season heats up is that King has long had a good relationship with Trump.

At a rally in Council Bluffs, Iowa, last year, with King in the crowd, Trump said he might be "the world's most conservative human being." And King has often bragged, without contradiction from the White House, about his influence with the president. But the White House didn't let King fly on Air Force One in June when Trump headlined a fundraising dinner in Iowa — a snub clearly intended to show distance between the commander in chief and a congressman who has become the party's chief internal irritant.

There's not much more Republicans can do to the iconoclastic congressman. The question is how much more damage he can do to them.