The president and CEO of the National Constitution Center is stepping down early next year to pursue other interests, the museum announced today.

It is the second time Joseph Torsella, 45, has left the Philadelphia institution. He first led the nonprofit from a concept in 1996 to the opening of its doors in 2003.

He resigned then to run for a U.S. House seat, but lost in the 2004 Democratic primary to Rep. Allyson Schwartz.

Torsella returned to the Constitution Center in 2006, when officials said his tenure would be transitional. Thursday's announcement said Torsella will remain involved in the search for a successor.

"This place will always feel like home, and I will be proud for the rest of my life of what I've been part of here," Torsella said. "But for me, it's time to move on and find new challenges."

Torsella is also chairman of the State Board of Education, which sets state education policy and regulations for K-12 public schools and higher education.

The National Constitution Center is dedicated to increasing public understanding of the U.S. Constitution and the ideas and values it represents.

Its sits near Independence Hall and the Liberty Bell, and its museum exhibits include a copy of the Emancipation Proclamation signed by President Lincoln and a notorious "butterfly ballot" from the disputed 2000 presidential election.

During Torsella's second stint, the center began sponsoring the Liberty Medal, awarded to those who have "demonstrated leadership and vision in the pursuit of liberty of conscience or freedom from oppression, ignorance, or deprivation." Recipients include Mikhail Gorbachev, Bono and former presidents George H.W. Bush and Bill Clinton.

The center also hosted a Democratic presidential primary debate between Sens. Hillary Rodham Clinton and Barack Obama, and it is where Obama gave his widely praised speech on race relations.