WASHINGTON — Republican Sen. Susan Collins, a key vote on President Donald Trump's pick for the Supreme Court, said Sunday she would oppose any nominee she believed would overturn the landmark Roe v. Wade decision that legalized abortion.

The White House is focusing on five to seven potential candidates to fill the vacancy of retiring Justice Anthony Kennedy, a swing vote on the court. The Maine senator said she would only back a judge who would show respect for settled law such as the 45-year-old Roe decision, which has long been anathema to conservatives.

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

Such a judge, she said, “would not be acceptable to me because that would indicate an activist agenda.”

Trump spent the weekend at his New Jersey golf club conferring with his advisers, including White House counsel Don McGahn, as he considers his options to fill the vacancy that might make precedent-shattering court decisions on abortion, health care, gay marriage and other issues.

The president told reporters Friday that he was homing in on up to seven candidates, including two women, and would announce his choice on July 9.

Trump is expected to begin his search in earnest this week at the White House and said the process could include interviews at his golf club before he reaches a final decision following the Fourth of July holiday.

During his 2016 campaign and presidency, Trump embraced anti-abortion groups and vowed to appoint federal judges who will favor efforts to roll back abortion rights. But he told reporters on Friday that he would not question potential high-court nominees about their views on abortion, saying it was “inappropriate to discuss.”

The Supreme Court legalized abortion in 1973, but anti-abortion advocates hope Roe v. Wade will soon be overruled if Trump gets the chance to appoint a justice who could cast a potentially decisive vote against it.

Without Kennedy, the high court will have four justices picked by Democratic presidents and four picked by Republicans, giving Trump the chance to shift the ideological balance toward conservatives for years to come. Both Chief Justice John Roberts and Justice Neil Gorsuch, Trump's first pick to the high court, have indicated more broadly that they respect legal precedent.

On Sunday, Leonard Leo, an outside adviser to Trump on judicial nominations, said he expected Trump to select a nominee who is mindful of precedent but who is also more “originalist and textualist.” That judicial approach typically involves a more literal interpretation of the Constitution as compared to broader rulings such as Roe.

Possible nominees being eyed include Thomas Hardiman, who serves alongside Trump's sister on the Philadelphia-based 3rd U.S. Circuit Court of Appeals, and Raymond Kethledge, a federal appeals court judge who clerked for Kennedy. Also of interest are Amul Thapar, who serves on the federal appeals court in Cincinnati; Brett Kavanaugh, a former clerk for Kennedy who serves on the federal appeals court in Washington, D.C.; and Amy Coney Barrett, who serves on the federal appeals court in Chicago.

Echoing Leo's view, Sen. Lindsey Graham, R-S.C., a member of the Judiciary Committee, said he didn't think Trump would be overly focused on the Roe ruling.

“You don't overturn precedent unless there's a good reason,” Graham said. “I would tell my pro-life friends: You can be pro-life and conservative, but you can also believe in ‘stare decisis,’” he said, citing the legal term involving legal precedent that means “to stand by things decided.”

Republicans hold a narrow 51-49 majority in the Senate, and it's even closer because of the absence of ailing Sen. John McCain of Arizona. Even though McConnell changed Senate rules last year to allow confirmation by simple majority, if Democrats hold together, he cannot afford defections. Vice President Mike Pence can be called on to break a tie.

Collins appeared on ABC's “This Week” and CNN's “State of the Union,” Leo spoke on “Fox News Sunday” and Graham was on NBC's “Meet the Press.”