As I worked my way through an archival box filled with accounts of her endless, exhausting campaign travel that year, I pulled out the yellowing pages, unfolded them, and discovered what was in effect a conversation with herself.

“Thoughts on abortion,” she wrote across the top of the first page, underlining the words.

Read: Barbara Bush changed with her country

Her deliberations might astonish cynics who assume that, for those who operate in the world of elective office, the calculations on such contentious topics are always political. The notes provide a window into how seriously she took the issue, and how she saw it as a moral question. The careful thought process they reflect may be the reason she never wavered in her views.

Her husband would, modifying his stance on abortion after Ronald Reagan chose him as his running mate at the Republican National Convention that summer. Before then, George Bush had tried to navigate a position down the middle. He opposed abortion but also opposed passing a constitutional amendment to ban it. He was against federal funding for abortion in general but supported exceptions in cases of rape or incest, or to preserve the health of the mother.

When Reagan asked him to join the GOP ticket, though, Bush promised to support the party platform, which endorsed a constitutional amendment that would overturn the 1973 Roe v. Wade Supreme Court decision recognizing abortion rights. By 1988, when Bush was the presidential nominee himself, the GOP platform would go even further. It asserted that “the unborn child has a fundamental individual right to life which cannot be infringed.”

Barbara Bush had no reservations about embracing her husband’s positions on the economy and foreign affairs, and most of all about extolling his virtues as a person and a leader. But on cultural and social issues, she often found herself at odds with the GOP and its increasingly conservative tilt. “In all our years of campaigning, abortion was the toughest issue for me,” she said later.

Read: The Republican party’s abortion bind

At the 1980 Republican convention, in Detroit, when George Bush’s prospects to be picked as Reagan’s running mate seemed to have faded, Barbara Bush arrived at a luncheon hosted by the National Federation of Republican Women sporting a pro-choice button. With her husband’s political ambitions apparently vanquished, she felt free to make her own stance on the issue clear.

That burst of independence was over almost before it began. That night, after negotiations with former President Gerald Ford to join the ticket collapsed and Reagan tapped Bush, her pro-choice button disappeared. She didn’t change her views, but she did stop talking about them, saying that only the opinion of those on the ballot mattered. While many assumed she still supported abortion rights—a reassuring thought to some moderate and liberal Republicans—she would rebuff attempts by reporters and activists to engage publicly on the issue until she published her White House memoirs 14 years later.