By JIM KUHNHENNWASHINGTON (AP) â¿¿ President Barack Obama will replace Gene Sperling, his chief economic adviser and West Wing workaholic, with Jeffrey Zients, a top aide who has filled in as acting budget director and who led a White House effort to streamline government. Zients would replace Sperling as director of Obama's National Economic Council, a post Sperling held for nearly three years, serving as Obama's economic whisperer during difficult fiscal wrangles with Congress. Sperling plans to leave Jan. 1. Obama announced the change Friday, describing Sperling as "one of my closest advisers and a close friend." He praised Zients as an admired and respected aide in the White House with "a sterling reputation as a business leader." Zients is a long-time management consultant who joined the White House in 2009 as chief performance officer, heading an effort to streamline government and cut costs. Obama later chose him twice as acting director of the Office of Management and Budget and he has been considered for other top posts. Sperling served in the same top economic post under President Bill Clinton. He's said to be leaving for personal reasons. His wife, a writer and producer, works in Los Angeles, and Sperling has been commuting between Washington and California. Before becoming director of the National Economic Council, Sperling worked at the Treasury Department advising then-Treasury Secretary Tim Geithner during the first two years of the Obama administration. "Gene's relentless work ethic, sharp intellect and ability to work across the aisle have been instrumental in our efforts to build a better bargain for the middle class and reduce the deficit while also protecting the most vulnerable," Obama said in a statement. "I want to thank Gene and his family for their service and I look forward to having his counsel for the rest of the year."