Bill Gross and Mohamed El-Erian, co-chief investment officers of bond giant Pimco, have not been approached by the Obama administration to succeed outgoing economic adviser Larry Summers, people familiar with the matter said Tuesday.

Speculation has been rampant that President Barack Obama will tap Summers' replacement from Corporate America. Gross and El-Erian, who oversee more than $1.1 trillion at Pacific Investment Management Co., have been mentioned as top choices, given their influence on world financial markets.

In August, Gross was among a group of 12 speakers testifying at a U.S. Treasury Department forum on the future of the housing finance system.

Mark Porterfield, spokesman at Pimco, said the firm does not comment on rumors or speculation. Summers, who coordinates economic policy for the president as head of the White House National Economic Council, announced last week that he is stepping down at the end of the year to return to Harvard University, where he is a professor.

With midterm elections looming, Obama's administration officials are said to be weighing whether to put a prominent corporate executive in the National Economic Council director's position to counter criticism that the administration is anti-business.

Summers on Tuesday played down the notion that Obama was intent on hiring a businessperson to replace him. While business experience could be valuable in the job, Summers told Reuters, "the president will hire whoever he thinks best."