(Recasts to note second source, White House saying no decision, adds spokesman comment, background)
By Patrick Rucker and Caren Bohan
WASHINGTON, Jan 27 (Reuters) - Software company president John Thompson is President Barack Obama's top choice for commerce secretary, senior Democratic sources said on Tuesday.
"He (Thompson) is the leading candidate," one Democratic source said. "He is still being vetted."
White House spokesman Robert Gibbs said a final decision had not been made.
"To the best of my knowledge no decisions have been made about a commerce secretary," Gibbs told a briefing. "I believe his name has been out there as among the candidates that the administration has thought about, but according to the latest thinking that I had, no decision on that had been made."
Thompson is chairman and chief executive officer of Symantec Corp, the No. 1 software security company, best known to consumers for its Norton product line.
Symantec announced late last year that Thompson, who was among the first Silicon Valley executives to throw his support behind Obama's bid for the presidency, would step down in early April.
Symantec spokesman Cris Paden declined to confirm or deny that Thompson is Obama's top pick for the post.
"I don't have any information," he said in an email.
A company official earlier had said the executive visited Washington in the last several weeks and noted Thompson's work on Obama's behalf.
Obama had nominated New Mexico Governor Bill Richardson to fill the commerce post, but Richardson withdrew on Jan. 4 in the face of a legal inquiry.
Richardson, a former Democratic presidential candidate and one of the country's most prominent Hispanic politicians, denied any wrongdoing in connection with the probe of a California financial company that had done business with New Mexico's state government.
But Richardson said an investigation lasting possibly weeks or even months "would have forced an untenable delay in the confirmation process."
Richard Parsons, the incoming chairman of Citigroup, had been rumored to be a potential Commerce pick after Richardson withdrew but the executive has said that was not interested.
Thompson's biography on Symantec's website says he built the company "from a small consumer software publisher to a global leader in providing security, storage and systems management solutions."
Thompson was a senior executive with IBM Corp before joining Symantec and has a master's degree in management science from MIT's Sloan School of Management.
Former President George W. Bush appointed Thompson to the National Infrastructure Advisory Committee in September 2002 to make recommendations on the security of the critical infrastructure of the United States.
Thompson also has served as the chair of the Silicon Valley Blue Ribbon Task Force on Aviation Security and Technology to identify and evaluate technology-driven solutions to improve the security and efficiency of national and local aviation.