President Obama has selected Solicitor General Elena Kagan to succeed retiring U.S. Supreme Court Justice John Paul Stevens, according to reports by Politico and NBC News Sunday.

The 50-year-old progressive -- who would be the court's youngest current justice -- could serve for decades if confirmed by the Senate, making her one of the president's lasting legacies.

If confirmed, she would be the fourth woman to ever serve on the nation's highest court. Obama is expected to announce the selection on Monday.

Court watchers have long eyed Kagan for the pick, speculating the Obama administration has been nurturing her for an associate justice slot since the president first plucked her from Harvard Law School where she had served as dean.

Before Kagan's role as solicitor general, she'd never appeared before the Supreme Court. And she's never been a judge -- an attractive attribute for those who believe the court needs more professional diversity among its ranks. All of the court's current line-up served on the bench prior to joining the Supreme Court.

In a lengthy post Saturday about Kagan, SCOTUSblog's Tom Goldstein, wrote that the fact that Kagan lacks a significant paper trail means "there is little basis on which to launch attacks against her, and no risk of a bruising Senate fight, much less a filibuster."