United States Trade Representative Ron Kirk is to step down in late February after nearly four years in the position.

A former Dallas Mayor, Kirk has headed the agency since March 2009, and is the first African American to hold the post.

"We have made great strides to bring about the President's vision of a more robust, responsible, and responsive trade policy that opens markets to products stamped 'Made-in-America' and enforces Americans' trade rights around the world - and does so in a way that is more consistent with America's core values on issues like the rights of workers and the environment," Ambassador Kirk said.

"In President Obama's first term, trade has been a major part of this Administration's efforts to support American jobs right here at home. I am proud of USTR's contribution to America's ongoing economic recovery."

The US trade representative is member of President Obama's cabinet and serves as the President's principal trade advisor, negotiator and spokesperson on trade issues.

The office of USTR is responsible for developing and overseeing US trade policy, including strategy, negotiation, implementation and enforcement of multilateral, regional/bilateral and sector-specific trade agreements.

Over the last four years these have included trade agreements with Korea, Colombia, and Panama, and the launch of the Trans-Pacific Partnership (TPP) trade negotiations.