President Obama officially announced his new chief of staff at the White House on Friday while flanked by two adorably self-effacing geeks, both of whom clutched their hands together looking kind of like shy tweens whose crush had finally noticed them. On Obama's left was Jack Lew, his old chief of staff, and on his right was Denis McDonough, his new one. To be fair, they are both very serious people — Lew is going to head the Treasury after Tim Geither's last day today, and the White House chief of staff is one of the most powerful unelected positions in the whole world. McDonough is also really into sports, and bikes to work even in "the most treacherous conditions," Marc Ambinder reports. Obama's been working with McDonough for 10 years and "trusts him more than just about any other adviser," Ambinder writes. Despite all that power and intensity and seriousness, the new guy looked a lot like a happy-but-self-conscious geek as Obama talked about how awesome he was: