WASHINGTON – President Barack Obama nominated White House chief of staff Jack Lew to be treasury secretary Thursday, declaring his complete trust in an aide with three decades of Washington experience in economic policy and a penchant for shunning the limelight.

“He is a low-key guy who prefers to surround himself with policy experts rather than television cameras,” Obama said.

Obama announced his nomination in the ornate White House East Room, flanked by Lew and outgoing Treasury Secretary Timothy Geithner. The two men and their backgrounds illustrate the nation’s changing economic landscape. Geithner is a longtime banking specialist with the Treasury and the Federal Reserve who took office in 2009 at the height of the nation’s financial crisis. Lew has been a budget expert as the government struggled with its debt and deficit challenges.