The view of some of the administration's China-handlers is that management of US-China policy has become so central to a vast array of other policy challenges that the administration's approach needs to be both broad and managed with "a deep and senior bench." The evolution of many functional offices at the Department of State and Treasury tasked with various line items in the China-US Strategic and Economic Dialogue has helped stabilize many aspects of the relationship and has helped to benchmark meeting to meeting progress on core concerns.
National Security Advisor Thomas Donilon has essentially been holding the China policy portfolio himself since September 2010 when in the early part of that month he and then Obama national economic advisor Lawrence Summers went to Beijing to attempt a reset in a quickly deteriorating US-China economic and military relationship. For the most part, currency politics aside, Donilon's mission has succeeded -- and he has since preempted either Clinton's China hands, particularly Assistant Secretary of State Kurt Campbell, or Geithner's team from taking primacy over US-China policy.
The shift to a strategy of engagement with Biden at the top, orchestrated by Donilon, allows the US to deal with China's likely next president from a Vice President to a Vice President/Next President status -- and to continue both the Departments of State's and Treasury's ongoing engagement with other designated key Chinese leaders.
After President Obama's 2008 presidential win, the original intention of the White House was to focus the Vice President primarily on domestic matters -- telling this writer at the time to remember that Joe Biden had recently been featured in Working Mother magazine. Part of the concern at the time was that with such personalities as Defense Secretary Bob Gates, Secretary of State Hillary Clinton, then National Security Advisor General Jim Jones, super-general-in-the-field David Petraeus, CIA Director Leon Panetta, Envoys Richard Holbrooke, former Senator George Mitchell, Stephen Bosworth, and Dennis Ross -- Joe Biden as a roving foreign policy/national security hand wasn't perceived to be stabilizing to a strong-on-divas Obama team.
However, Joe Biden quietly took on national security tasks that were key to President Obama and that needed more off the newspaper front page handling. These included laying the groundwork for the major nuclear materials summit that the Obama administration hosted in April 2010 as well as lining up the continuity of thinking and policy deployment tying together this nuclear materials and WMD summit with President Obama's Nuclear Posture Review and the Senate passage of the New START treaty. Biden also played a leading role -- along with Defense Secretary Bob Gates -- in the "Russia reset."