Justice Sandra Day O’Connor, a critical swing vote on several hot-topic issues including abortion and church-state separation, announced today that she is resigning.

"It has been a great privilege indeed to have served as a member of the court for 24 terms," the 75-year-old justice wrote Bush in a one-paragraph resignation letter. "I will leave it with enormous respect for the integrity of the court and its role under our constitutional structure."

Hours after her announcement, Bush praised O'Connor as "a discerning and conscientious judge and a public servant of complete integrity." While he did not give specific names, Bush said he would recommend a replacement who will “faithfully interpret” the laws.

O’Connor is the first woman on the Supreme Court. Her retirement will mark the first opening in 11 years at the aging high court, and will set off what is expected to be a bruising fight over confirming her successor.

This battle over judicial nominees topped priorities lists of several evangelical Christian groups this year.

“The reason why judges are our number one issue is because judicial decisions tie into just about anything you can name, be it the separation of church and state, marriage, abortion, taxation and education,” said Tom McClusky, Director of Government Affairs at the Family Research Council.

Echoing Bush’s comments, McClusky said the nominee should be a “strict constitutionalist” who plays the role of a judge and not a legislator.

“If we find a nominee we can support, we will do all we can – running radio ads, lobbying – until a strict constitutionalist is approved by the Senate,” said Tom McClusky.

Meanwhile, Richard Cizik, Vice President of Governmental Affairs at the National Association of Evangelicals, agreed the issue of justices is critical, but said his group will not likely endorse or promote any candidate. Rather, he said the NAE will likely outline and list favorable principles a nominee should have.

Topping that list is a respect for religious freedom.

“There is a push to eradicate religion from public life,” said Cizik. “Our hope is that we will have a replacement who increasingly understands the role of the court on subjects like church and state.”

“We don’t want a strict separation, and an appointee should respect religion in public life,” said Cizik.

Earlier this week, O’Connor voted against the public display of Ten Commandments monuments in two separate cases.

Although O'Connor was appointed by President Ronald Reagan, she became a moderate voice in the High Court and the critical swing vote that determined many 5-4 decisions. She also consistenly voted for abortion rights, but ruled against partial birth abortion.