After Supreme Court Justice Anthony Kennedy announced his retirement this week, the largest unanswered question in American life instantly became whom Donald Trump would choose to appoint in his place—and how the nominee would vote on a few very specific issues. Roe v. Wade, the landmark Supreme Court decision affirming the constitutionality of abortion, was a hot-button topic during Trump’s campaign and may be a deciding factor in whom he chooses to succeed Kennedy on the Supreme Court. On Sunday, Republican Senator Susan Collins said she would not support a nominee whose goal would be to overturn one of the court’s biggest decisions.

While appearing on CNN’s State of the Union, Collins told Jake Tapper that she and the president had spoken about his Supreme Court picks, and that she urged him to cast a wider net beyond the list of 25 possible nominees he’s already considering. With Republicans holding a razor-thin, one-vote margin in the Senate, Collins and fellow moderate Lisa Murkowski of Alaska will hold enormous sway as Trump’s Supreme Court pick faces his or her confirmation.

“The president really was soliciting my views on the type of nominee that I was looking for,” Collins said. “I emphasized that I wanted a nominee who would respect precedent, a fundamental tenet of our judicial system.” When Tapper challenged her, reminding her that Trump and Mike Pence had made Roe a talking point on their campaign (Trump affirming that it would be used as a “litmus test” and Pence assuring a rally of supporters that it would be “consigned to the ash heap of history”), Collins said that Trump had told her he wouldn’t address the issue when speaking to his nominees.

“The president told me in our meeting that he would not ask that question,” she said. “And that is what he most recently said on the advice of his attorney. So, I think what he said as a candidate may not have been informed by the legal advice that he now has, that it would be inappropriate for him to ask a nominee how he or she would roll on a specific issue.

“I would not support a nominee who demonstrated hostility to Roe v. Wade,” she continued, “because that would mean to me that their judicial philosophy did not include a respect for established decisions, established law.”

Trump has said that he will announce his pick on July 9.