Donald Trump’s decision to weigh in on the abortion issue again at this juncture, with his most definitive statement yet that he opposes a fifteen-week federal ban favored by some Republicans, is a political mistake for several reasons.

As wise as his transactional embrace of pro-life voters was in 2016 — ultimately proving the difference between his historic win and what the media and many establishment Republicans widely expected to be an ignominious loss — his statement this morning is a misstep which could ultimately undermine his attempt to return to the White House, and therefore for the pro-life movement’s ability to...