Updated: 12 p.m.Battle lines over President Barack Obama’s first Supreme Court nominee were quickly solidifying Friday morning, even as the White House and Capitol Hill continued to wait for the official word that Justice David Souter would retire this summer.Majority Leader Harry Reid (D-Nev.), caught outside the Senate chamber Friday morning, said of the news: “It’s a loss for the country. He’s the only friend I have on the Supreme Court.— White House officials were so far withholding comment on the Souterretirement, pending formal notification from the high court.“The president has not received a formal communication from JusticeSouter and he deserves the right to make his own announcement,— a White House aide said.While politicians at both ends of Pennsylvania Avenue may be waiting to comment until Obama receives a formal communication on Souter’s intentions, interest groups were wasting no time drawing lines in the sand over a looming Senate confirmation fight.Charmaine Yoest, president of Americans United for Life, warned in a statement Friday morning that anti-abortion-rights organizations would vigorously oppose any nominee that interprets the Constitution to include protections for abortion.“We will work to oppose any nominee for the Supreme Court who will read the Freedom of Choice Act into the Constitution in order to elevate abortion to a fundamental right on the same plane as the freedom of speech. In his search for a replacement for Justice Souter, President Obama should avoid a pro-abortion litmus test,— Yoest said.Marge Baker, executive vice president at People for the American Way, urged Obama to stick by his campaign pledge to tap nominees who bring a level of empathy for minorities, the poor and women.“To fill Justice Souter’s seat on the Court, President Obama should nominate someone who can continue his work to defend our personal freedoms and ensure that every person has equal access to justice,— Baker said. “Our country needs another jurist who appreciates the impact that the law and the Constitution have on every American, not just a few. In November, President Obama was given a mandate to appoint federal judges who are committed to our core constitutional values of justice, equality, and opportunity for all. That is exactly what he should do.—Souter, 69, was nominated by President George H.W. Bush in 1990, and has been a reliable liberal vote on the court since then. His relative youth — several of the justices including John Paul Stevens and Ruth Bader Ginsburg are significantly older — makes his decision to leave the court something of a surprise. But while speculation about Obama’s first high court vacancy has so far centered on Stevens and Ginsburg — who was recently diagnosed with pancreatic cancer — Souter has never “fit— into the life of official Washington, opting to spend much of his free time in his native New Hampshire.There has been speculation among Supreme Court watchers that Souter would step down this year, but neither he nor anyone else associated with the court has ever confirmed that.The biggest clue has been that Souter, unlike his colleagues, has not yet hired the four law clerks who will work with him in the new term, which begins on Oct. 5.Souter’s retirement would give Obama an opportunity to put his stamp on the nine-member court. Seven of its members were appointed by Republican presidents, including Chief Justice John Roberts, who was nominated by George W. Bush.It will also prove to be an early, and perhaps major, test of party-switcher Sen. Arlen Specter’s (Pa.) fealty to the Democratic Party, as well as the new Republican leadership of the Senate Judiciary Committee, which will be responsible for vetting Obama’s pick. Specter had served as the GOP’s top Republican on the Judiciary panel, a post he gave up when he bolted to the Democratic ranks earlier this week. The most likely successors are Sens. Jeff Sessions (R-Ala.) and Orrin Hatch (Utah), both conservatives who have taken a tough stand on judicial nominees in the past. Keith Koffler contributed to this report.