Kirk mum on when he will leave USTR

Asked if he would stay until the next round of the Trans-Pacific Partnership (TPP) talks in Singapore in March, he repeated his answer and added a laugh, zipping into the lunch that included the power center of Washington politics.

At least two names have been mentioned as possible successors: USTR deputy Michael Punke and White House trade adviser Mike Froman, who went to Harvard Law School with Obama.  

Since he was sworn into the position in March 2009, Kirk has helped usher through Congress the three free-trade agreements that had languished through the end of former President George W. Bush's tenure.

In October 2011, lawmakers cleared trade deals with South Korea, Colombia and Panama. He also pressed Congress to grant permanent normal trade relations to Russia, which joined the World Trade Organization in August after nearly two decades of lobbying. 

Kirk's main focus is the TPP deal, which heads into its 16th round of negotiations in March. In recent months, Canada and Mexico have gotten seats at the table, and Japan also is considering whether it would benefit them to join the talks.