GOP Sen. Susan Collins, expected to be a crucial vote in confirming a Supreme Court nominee in the Senate, said on Sunday she would be unable to support any candidate who vowed to overturn the landmark decision legalizing abortion nationwide.

“A candidate for this important position who would overturn Roe v. Wade would not be acceptable to me because that would indicate an activist agenda that I don’t want to see a judge have, and that would indicate to me a failure to respect precedent,” Collins said on ABC’s “This Week.”

The pro-choice Maine lawmaker said her support for a nominee to replace Justice Anthony Kennedy, who announced his retirement last week, will hinge on whether the person follows legal precedent.

“I’m going to have an in-depth discussion with the nominee and I believe very much that Roe v. Wade is settled law, as it has been described by Chief Justice Roberts,” she said. “It has been established as a constitutional right for 46 years — 45 years, and was reaffirmed 26 years ago.”

President Trump told reporters aboard Air Force One on Friday that he would not ask candidates where they stand on the 1973 abortion ruling.

“[Trump] did tell me that he would not be asking that question,” Collins said. “And indeed it would be inappropriate to ask a judge nominee on how they are going to vote in a future case. A discussion of precedent, however, is very important.”

Sen. Lindsey Graham also said Roe v. Wade shouldn’t be overturned “unless there is good reason.”

“You don’t overturn precedent unless there’s a good reason,” the South Carolina lawmaker said on NBC’s “Meet the Press.” “I would tell my pro-life friends: You can be pro-life and conservative, but you can also believe in stare decisis,” he added, using a legal term referring to precedent.

Democratic Sen. Maria Cantwell warned lawmakers ​of both persuasions that a vote to confirm a justice who pushes aside precedent and overturns Roe v. Wade could be “career-ending.”

“My colleagues on both sides of the aisle know that this vote could be one of the key votes of their entire career,” Cantwell ​of Washington ​​said on ​NBC. “If they vote for somebody who’s going to change precedent, it could be a career-ending move.”

Kennedy, 81, played an important role in providing a swing vote on a number of important cases, and with his retirement, many believe the court could become more conservative and overturn past rulings like Roe v. Wade.

He was a member of the court in 1992 that voted to reaffirm the decision.

Collins also suggested Trump expand his search beyond a list of 25 judges he initially used to find a candidate.

“Some people on the list I can’t support because they have shown disrespect for the vital principle of stare decisis,” Collins said on ABC. “I’m not going to go into which ones those are, but there are people on that list whom I could not vote for.”

Trump said he has narrowed the list to about five, including two women, and added he intends to announce the nominee on July 9 before he heads to Europe for a NATO meeting and a summit with Russian President Vladimir Putin.

Senate Majority Leader Mitch McConnell said he would call for a vote before the midterm elections in November. Republicans, who control the Senate by a 51-49 margin, only need a majority to confirm Trump’s court pick.

Both Republicans and Democrats are pursuing Collins and Sen. Lisa Murkowski, a Republican from Alaska who also favors abortion rights, for their votes.

The two parties are also lobbying Democratic Sens. Joe Manchin of West Virginia and Joe Donnelly of Indiana, who are up for re-election in states carried by Trump.

The two, along with Democratic Sen. Heidi Heitkamp of North Dakota, voted to confirm Neil Gorsuch, whom Trump selected in January 2017 to replace Justice Antonin Scalia, who died in February 2016.