WASHINGTON — Sen. Bob Casey will vote to support a bill to ensure access to abortion nationwide, he said Tuesday, taking a significant step in favor of abortion rights despite long describing himself as a “pro-life” Democrat.

Casey, whose namesake father was part of a landmark Supreme Court case on abortion restrictions, announced his stand Tuesday ahead of a Senate vote, expected as soon as Wednesday, that would attempt to write into law the Supreme Court’s 1973 Roe v. Wade decision legalizing abortion and blocking many bans.

While the vote is certain to fail in the face of opposition from Republicans and likely from West Virginia Democrat Joe Manchin, it represents Democrats’ first formal pushback against a forthcoming Supreme Court decision that appears poised to overturn the pivotal abortion ruling.

Casey, in a statement, said he has never voted for and would not support “a categorical ban on abortion” that could result from the expected ruling.

Casey’s statement is a notable marker of where he stands on the issue, given his complicated past on abortion votes. Earlier this year, he voted to advance debate on the same bill, the Women’s Health Protection Act, but had not said if he supported the underlying proposal.

He clarified that Tuesday.

The upcoming vote comes at a fraught moment, a week after a leaked draft of a Supreme Court opinion signaled that conservative justices could soon wipe out the decision protecting abortion, leading to restrictions and possibly outright bans in many states.

» READ MORE: Casey is one of the last ‘pro-life’ Democrats. The Supreme Court decision is going to test his views.

Casey cited that likelihood in explaining his vote.

“This week, I will again vote yes to advance debate on the Women’s Health Protection Act and I will support the bill if there is a vote on final passage in the future,” he said in a statement.

“In the nearly three months since the Senate last voted on the Women’s Health Protection Act, the circumstances around the entire debate on abortion have changed,” he added. “In light of the leaked Supreme Court decision draft overturning Roe v. Wade, and subsequent reports that Republicans in the U.S. House and Senate will introduce legislation to enact a nationwide six-week ban, the real question of the moment is: Do you support a categorical ban on abortion? During my time in public office, I have never voted for — nor do I support — such a ban.”

His stand was immediately praised by liberals and is sure to draw scorn from antiabortion groups, which have long accused Casey of failing to live up to his professed beliefs.

Casey has been viewed as a relatively moderate Democrat, in part because of the legacy of his father, former Gov. Bob Casey. He has shifted leftward on many issues over the last decade but continues to call himself “pro-life.” That stand came under intense scrutiny after the leak last week revealed the direction the Supreme Court seems poised to take.

» READ MORE: Bob Casey wants Biden and Democrats to swing for the fences: ‘Go big or go home’

When Senate Democrats rallied on the Capitol steps after the leak, Casey was one of the few who didn’t attend.

He has walked a fine line on abortion, at times voting in favor of restrictions, such as a proposed ban after 20 weeks in 2018 but also supporting funding for Planned Parenthood and other steps that, he argues, provide crucial health care and planning that can reduce the need for abortions.

He has previously opposed more drastic steps, like a near-total ban passed in Alabama in 2019, and has earned mostly positive marks from Planned Parenthood and NARAL Pro-Choice America, the latter of which gave him a 72% rating in 2020.

Casey’s father signed the abortion restrictions that were upheld in the landmark Planned Parenthood v. Casey Supreme Court decision in 1992, adding to the personal weight around the issue.