Supreme Court Justice David Souter plans to retire from his seat on the country's highest court when it completes its current term, according to news reports. Hearing the announcement, some pro-life groups are promising to vigorously oppose any Obama appointee that does not support the right to life of the unborn.

Souter's retirement comes as a bit of a surprise since he is 69—younger than both of the other liberal Justices Ruth Bader Ginsberg and John Paul Stevens, who are 76 and 89 respectively.

Currently, the court has finished hearing oral arguments for the term and will spend the time between now and June issuing rulings and opinions.

Almost as soon as news of Souter's retirement hit the wires, speculation began about who President Obama would appoint to replace him.

At a speech to Planned Parenthood in July of 2007, then-Senator Obama explained to the crowd what his ideal Supreme Court justice looked like.

"And then there's another vision of the court that says that the courts are the refuge of the powerless. .... And we need somebody who's got the heart -- the empathy -- to recognize what it's like to be a young teenage mom. The empathy to understand what it's like to be poor or African-American or gay or disabled or old -- and that's the criteria by which I'll be selecting my judges."

Later, while on the campaign trail in Ohio in 2008, Obama further described this type of justice, saying, "I want people on the bench who have enough empathy, enough feeling, for what ordinary people are going through."

Observers note that since the president is likely to appoint a liberal to replace Souter, the ideological balance of the court will not likely change from its current makeup.

Troy Newman, president of the pro-life group Operation Rescue, argued that recent polling data showing a slip in public support for legal abortion means that Obama will have to be careful about where his nominee stands on the issue.

"Obama has been spanked over the past 100 days on the issue of abortion. There has been a growing grassroots opposition to his invitation to speak at Notre Dame, along with the Sebelius fiasco. On Wednesday he backed away from the Freedom of Choice Act, something he promised to sign as his first act as president, saying it was 'not the highest legislative priority,'" Newman stated in a press release.

Marjorie Dannenfelser of the Susan B. Anthony List pointed to President Obama's promise to seek "common ground" to work to reduce abortions and stated that choosing a nominee "who wants to enshrine the right to an unrestricted abortion in the United States Constitution would certainly be a step in the wrong direction."