Former Dallas mayor Ron Kirk, who emerged Thursday as President-elect Barack Obama ’s choice for chief trade negotiator, is something of an unknown quantity when it comes to trade policy.

A longtime aide to former senator and Treasury Secretary Lloyd Bentsen, D-Texas, Kirk ran unsuccessfully for the U.S. Senate in 2002 against Republican John Cornyn , and would bring substantial public policy, negotiating and lobbying experience to the job of U.S. trade representative. But he has not been a major presence on the trade scene.

With deep roots in Texas, Kirk — a pro-business Democrat like his mentor Bentsen — may bring a special perspective to dealing with U.S.-Mexican trade relations. During the presidential campaign, Obama worried free-traders by calling for the re-negotiation of the North American Free Trade Agreement.

Despite raising concerns about pending trade agreements with Colombia and South Korea and tough talk on China during the campaign, Obama has thus far selected Cabinet members who have generally favored pro-trade policies, including his pick for Commerce secretary, New Mexico Gov. Bill Richardson .

Obama was expected to formally announced his choice of Kirk at a Friday news conference in Chicago, a senior Democratic source said.

Obama had earlier offered the job to Rep. Xavier Becerra , a veteran California Democrat, but Becerra has made it clear he intends to stay in the House.

Kirk was one of Obama’s key political contacts in Texas throughout 2008. He endorsed Obama over rival Sen. Hillary Rodham Clinton , D-N.Y., before the Texas primary in March — and was mentioned as a possible candidate for Transportation secretary, a slot that will go to Rep. Ray LaHood , R-Ill.

After his years working with Bentsen in Washington, Kirk was tapped by former Texas Gov. Ann Richards to serve as Texas secretary of state in 1994, and then elected the first African-American mayor of Dallas.

While he doesn’t know Kirk, Bill Reinsch, president of the National Foreign Trade Council, says that the job requires two things: good negotiating skills and an ability to effectively engage members of Congress.

Kirk’s record as mayor of Dallas from 1995 to 2001, which included support for the construction of the American Airlines Center, leaves free-trade advocates hopeful that he will support a free trade agenda amid a growing chorus of trade skeptics in Congress.

Kirk supported the permanent normalization of trade relations with China in 2000, and “seems to be squarely in the mainstream of views on trade,” says John Murphy, vice president for international affairs at the U.S. Chamber of Commerce. Murphy added that Kirk would fit well among the “pragmatists” on the emerging Obama team, noting that Kirk has a record of working closely with the Dallas business community to “take advantage of trade opportunities.” He also said Kirk has voiced concerns about the impact of trade on workers and the environment.

A graduate of Austin College and the University of Texas law school, Kirk currently practices public finance and policy law at powerhouse Dallas lobbying shop Vinson and Elkins LLP. He has represented a range of corporate clients, including Southwest Airlines, the Texas Association of Realtors and the New Car Dealers Association of Metropolitan Dallas.

Kirk is on the board of directors for Brinker International, Dean Foods Company and PetSmart, Inc.