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Speculation is building that President Obama is leaning toward Solicitor General Elena Kagan as his pick to replace retiring Justice John Paul Stevens on the Supreme Court, with Kagan getting a high-profile endorsement from within the administration Sunday.

Attorney General Eric Holder, who is Kagan's boss at the Justice Department, said an announcement will come "very soon" and did little to dispel the notion that Kagan is the leading choice.

"She's done a wonderful job in the Justice Department. I've known her since the Clinton years. And I think she would be a great justice," Holder said on NBC's "Meet the Press."

He cited her credentials as solicitor general and the first woman to ever hold that post, as well as the position of Harvard Law School dean.

"I think people will get an understanding who she is, what her judicial philosophy is, if in fact she is the pick," Holder said.

Kagan just celebrated her 50th birthday, and her relative youth is seen as a plus for the lifetime appointment. She has interviewed separately with Obama and Vice President Biden and was a finalist for the 2009 opening that was filled by Justice Sonia Sotomayor.

Last year, the Senate confirmed Kagan's appointment as solicitor general with relative ease. It was well known at the time that Obama might eventually send her name to Capitol Hill again.

Three other candidates have also gone through multiple interviews at the White House in recent weeks. They are: D.C. Circuit Court of Appeals Judge Merrick Garland, 9th Circuit Court of Appeals Judge Sidney Thomas and 7th Circuit Court of Appeals Judge Diane Wood.

If selected, Kagan, who is not married, would be the fourth woman ever nominated to the high court and continue a trend of Ivy League-educated lawyers who sit on the bench.

Unlike the others she would join, Kagan has never before served as a federal judge, an issue that is sure to come up in a confirmation hearing. It could also give her the outsider status and perspective that some senators have called for in a candidate.

Another interesting twist to a possible Kagan appointment centers on religion. She is Jewish, as are Justices Stephen Breyer and Ruth Bader Ginsburg. The other six justices are Roman Catholic, meaning a Supreme Court with Kagan would be the first ever without a Protestant.