* Top candidate Froman could stay in White House job
* Obama looking at candidates for both USTR, Commerce posts
By Doug Palmer and Jeff Mason
WASHINGTON, Jan 22 (Reuters) - U.S. Trade Representative Ron Kirk said on Tuesday he was stepping down as the nation's top trade official in late February, opening up a plum economic post as President Barack Obama searches for more women and minorities for his Cabinet.
White House international economic affairs adviser Mike Froman had been considered the front-runner to succeed Kirk, but sources familiar with his thinking said he was likely to stay in his current job, which allows him to weigh in on issues ranging from energy and climate change to trade and international finance.
One source familiar with the situation identified Treasury Under Secretary for International Affairs Lael Brainard, Commerce Under Secretary for International Affairs Francisco Sanchez and U.S. Export-Import Bank President Fred Hochberg as candidates for the USTR job.
Kirk, a former mayor of Dallas, Texas and early Obama supporter, oversaw congressional approval of free-trade agreements with South Korea, Panama and Colombia. He also completed negotiations on Russia's entry to the World Trade Organization.
"Ron was relentless in making the case to the American public that a balanced, thoughtful trade policy can contribute to a stronger economic future for America," Obama said in a statement praising his friend and golfing companion.
Leading the small, dedicated team of professional negotiators at the U.S. Trade Representative's office "has been no less than my greatest professional privilege," Kirk said in a statement that gave no detail of his future plans.
"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," he said.
Other possible candidates to succeed Kirk include Deputy U.S. Trade Representative Demetrios Marantis and the U.S. ambassador to the World Trade Organization, Michael Punke.
Obama, who is under pressure to name more women and minorities to his second-term Cabinet, may also look outside the administration to fill both the USTR job and that of Commerce secretary, which has been filled on an "acting" basis since John Bryson stepped down last year.
The source familiar with the matter said Hochberg, the Ex-Im president, Jeffrey Zients, a deputy director of the White House budget office, and Elizabeth Littlefield, president of the Overseas Private Investment Corporation, were all under consideration for the Commerce position.
Xerox chief executive Ursula Burns, who is vice chair of Obama's export council, was also being considered, and there was an ongoing search for business leaders outside the administration for the role, the source said.
Deputy Commerce Secretary Rebecca Blank is "acting" head of the sprawling department, and some industry officials think she may be chosen to fill the job permanently.
Kirk's tenure was marked by increased confrontation with China over trade issues, with the United States challenging Chinese policies that discriminate against American exports in areas ranging from wind power to autos.
Kirk overcame initial White House resistance to relaunching talks on a regional free-trade agreement known as the Trans-Pacific Partnership, which many experts consider the most significant trade negotiation now under way.
"It's very hard to pursue an activist international agenda when there's so much churning in the domestic economy. To his credit, he has maintained an open U.S. trade policy at a time of great stress," said Jeffrey Schott, a senior fellow at the Peterson Institute for International Economics.
Ed Gresser, trade policy director at GlobalWorks Foundation, said Kirk helped restore support for trade in Congress after bitter fights between Republicans and Democrats during President George W. Bush's administration.
"There's a steadily strengthening consensus in Congress that trade policy needs to be a part of the solution to our (economic) crisis and we need to be passing more trade bills and negotiating more agreements," Gresser said.
Kirk, a former Texas secretary of state, ran unsuccessfully for the Senate in 2001 but has downplayed chances that he might run for office again. He has joked with reporters about his desire instead to earn more money to pay for his two daughters' college bills.
Kirk has worked with European Union Trade Commissioner Karel De Gucht to lay the groundwork for possible negotiations on a transatlantic free trade agreement between the United States and the 27-nation European Union.
However, he was not able to crack the tough nut that is the Doha round of world trade talks. Those negotiations began in 2001 and still are unfinished, with the hope of a comprehensive market-opening agreement all but officially dead.