Kathryn Ruemmler, who as White House counsel has become a trusted member of President Obama’s inner circle, plans to step down by the end of the year to return to private practice, officials said Wednesday.

Ruemmler, who has served in the administration since the start of Obama’s presidency, has told him she intends to leave government service and move to New York, the officials said. Ruemmler wanted to leave at the end of 2012 after the election, but the president asked her to stay on longer, they said.

“She is an enormous asset and a very important adviser to the president, and one of the smartest people I’ve ever met and one of the best people I’ve ever worked with,” White House press secretary Jay Carney told reporters. “So we will all be sad to see her go when she goes.”

Ruemmler, 42, joined the Obama administration as the third-ranking official at the Justice Department and later moved to the White House, first as deputy counsel and later as counsel. She rose to prominence in the Washington legal establishment as one of three lead prosecutors in the case against Enron executives Kenneth Lay and Jeffrey Skilling, who were convicted on securities and wire fraud charges.

As White House counsel, Ruemmler advises Obama on a broad array of legal issues, including immigration policies, Cabinet and judicial nominations and his signature health-care law. Ruemmler is a member of Obama’s national security team and helps guide his counterterrorism decisions.

Ruemmler also serves as the legal protector of the president and his top appointees, shielding them from potential scandal.

News of Ruemmler’s departure was first reported by Politico.