Geithner ends speculation about his future by vowing to stay on as US Treasury chief (VIDEO)

U.S. Treasury Secretary Timothy Geithner said Sunday he would stay at his post after President Barack Obama asked him to reconsider plans to step down.

Geithner was rumored to have considered leaving public office after the government borrowing limit was increased, so he could spend more time with his family in New York.

But he ended the speculation Sunday, telling NBC/CNBC in an interview that he would remain at the helm of the U.S. Treasury.

"I love my work. And I think if a president asks you to serve, you have to do it," Geithner said, according to Reuters.

His decision comes at a time of global economic uncertainty fueled by bitter ideological infighting in Washington, a rating downgrade of U.S. debt and a spreading European debt crisis.

The White House confirmed that Obama had personally asked Geithner, the last member of his original economic team still in place, not to leave.

"The president asked Secretary Geithner to stay on at Treasury and welcomes his decision," White House press secretary Jay Carney said, according to The Washington Post.

Treasury spokeswoman Jenni LeCompte said Geithner "looks forward to the important work ahead on the challenges facing our great country."

Geithner wasted little time on his own affairs as he fronted reporters Sunday in the wake of Standard and Poor's decision to cut its rating of U.S. debt from AAA to AA+.

"They've handled themselves very poorly. And they've shown a stunning lack of knowledge about the basic U.S. fiscal budget math," Geithner said of the ratings agency, according to AP.

"Look at the quality of judgments they've made in the past," he added, an apparent reference to the top ratings agencies failure to spot weaknesses in the U.S. subprime mortgage market ahead of the 2008 financial crisis.

Senior Republicans last week called for Geithner to resign over the ratings downgrade, even though S&P blamed politicians for undermining the country's credit worthiness.