Arianna's right hand is out at The Huffington Post.
Huffington announced today via company memo that Tim O'Brien, executive editor of the online publisher, will be leaving the site to work on the second of his five-part book deal. Per the memo, Huffington noted, "In the next few days, Tim's reporters will transition to the editorial team of Howard Fineman, Peter Goodman, Ryan Grim, Kate Palmer, John Montorio, Sam Stein and Amanda Terkel."
O'Brien joined The Huffington Post early in 2011 from The New York Times, where he served as a reporter as well as the Sunday Business editor of the paper. At The Huffington Post, he was often cited as a crucial player in the focus on deeper reporting and investigative work, which culminated last April when the site won a Pulitzer Prize for David Wood's "Beyond the Battlefield" (O'Brien edited the series).
O'Brien's departure is a definite loss for the site, which in a nonelection year is constantly fending off competition from up-and-coming Web publishers while trying to hone and integrate assets like its online, streaming network HuffPost Live. During his tenure, O'Brien tried his hand at digital projects like Huffington, an iPad-only magazine that has yet to gain traction.
To help fill the gaps, Huffington also announced the site would be rehiring Financial Times reporter Shahien Nasiripour to cover national finance beats.
Huffington's full memo can be found here, as first reported by Capital New York.