Ironically, abortion bans/further abortion restrictions
might accelerate the Great Replacement, which is why white nationalists have not been unequivocally in favor of them:
https://www.amren.com/wp-content/uploads/2022/05/Protest-in-Favor-of-Roe-v-Wade-600x400.jpeg=Thousands of abortion rights protesters rallied at Foley Square in New York City on May 3, 2022, later marching to Washington Square Park, denouncing the leaked draft opinion written by Supreme Court...
www.unz.com
You need to keep in mind that the GOP is a big-tent party. It includes both white nationalists and conservative Christians. The two don't always see eye-to-eye on everything. The latter are more sympathetic to the Great Replacement than the former are, for instance, sometimes viewing it as a Christian duty to resettle refugees here in the West.