Politics of abortion: Can Republicans avoid going off a cliff?

Nikki Haley moves briskly through her talking points – on the federal budget, education, transgender matters, immigration. 

But at her “Women for Nikki” launch event last week in Des Moines, Iowa, the Republican candidate for president doesn’t voluntarily touch upon what may be the hottest topic in politics today: abortion.

Only when an audience member brings it up does Ms. Haley – former U.S. ambassador to the United Nations and former governor of South Carolina – address the subject. 

“I am strongly pro-life,” she says to applause, noting that her...