Washington • Sen. Susan Collins, R-Maine, a key swing vote on President Donald Trump’s next Supreme Court pick, said Sunday that she would not vote for any judge who wanted to end access to abortion in the United States by overturning Roe v. Wade.

“I would not support a nominee who demonstrated hostility to Roe v. Wade,” Collins said Sunday on CNN’s “State of the Union,” adding that Roe v. Wade established abortion as a “constitutional right.”

In another appearance, on ABC News’ “This Week,” Collins said that any judge who wants to overturn Roe has an “activist agenda” that she thinks goes against the fundamental tenets of U.S. law and the Constitution.

Trump has met with Collins to discuss potential candidates for the Supreme Court, and she said she let him know that she would not support some of the people on the list of 25 judges he’s considering for the critical role on the nation’s highest court. She said she urged him to expand his list.

On the 2016 campaign trail, Trump indicated he would take into account whether a judge would overturn Roe v. Wade when he considered them for a Supreme Court position, and his evangelical base is calling for him to honor his promise. But Trump has changed his rhetoric in the past week after Justice Anthony M. Kennedy announced his retirement.

Collins said Trump assured her that he would not ask nominees whether they would vote to overturn Roe v. Wade.

“The president told me in our meeting that he would not ask that question,” she said on CNN. In her ABC News appearance, Collins added that she feels it would be “inappropriate” for Trump to ask that question.

Supreme Court nominees must be confirmed by a majority in the Senate. Republicans have 51 votes, but Sen. John McCain’s health issues may prevent him from voting, meaning Trump would need every other GOP senator’s vote unless a Democrat crossed party lines. Collins and Lisa Murkowski, R-Alaska, are widely considered the critical swing voters. Both women bucked Trump by voting against the health-care overhaul bill last summer, and they have tended to support abortion rights.

Sen. Amy Klobuchar, D-Minn., a member of the Senate Judiciary Committee, appeared just after Collins on “This Week” and called her Republican colleague’s remarks in support of Roe v. Wade “very heartening.”

Trump has said that he views picking Supreme Court justices as the most important thing he will do as president outside of war and peace. He said at a rally in North Dakota last week that he wants to pick someone who will “be there for 40, 45 years.”

Trump said in an interview on Fox News’s “Sunday Morning Futures” that Kennedy “ended up being a little more neutral than a lot of people would have preferred.” Kennedy cast several decisive votes in support of gay rights and abortion.

Collins has been one of the most bipartisan senators in recent years, and many say this could be one of the most consequential votes of her tenure, one that will test her core values.

“My colleagues on both sides of the aisle know that this vote could be one of the key votes of their entire career,” Sen. Maria Cantwell, D-Wash., said during an appearance on NBC’s “Meet the Press.” “If they vote for somebody who’s going to change precedent, it could be a career-ending move.”

Leonard Leo, a lawyer advising the president on his Supreme Court pick, tried to play down the possibility of overturning Roe, saying the matter was largely settled.

“The fact of the matter is — Roe v. Wade is a major precedent,” Leo said on “Fox News Sunday.” “Part of interpreting the Constitution is taking into account major precedents, and that’s going to happen.”

But many on the left and the right believe that Trump’s shortlist of candidates is made up of judges who would be open to scaling back abortion rights because they have been vetted by Leo and conservatives already, so the president doesn’t need to ask the question openly.

“Trump ran on a platform of anti-choice judges and the promise of overturning Roe v. Wade, so it’s hard to imagine how someone would be on that list who he didn’t believe was anti-choice,” said Carl Tobias, a law professor at the University of Richmond who focuses on federal judicial selection.