"She has done an incredible job. She has logged a lot of miles, she has been working so hard, Obama told viewers on NBC television's "Tonight Show," a popular, late-night comedy program.

Less than two weeks before the November 6 vote that will determine whether he will win a second term in the White House, Obama heaped praise on Clinton, who four years ago was his bitter rival for the Democratic presidential nomination.

Obama ultimately won the nomination before defeating Republican nominee John McCain in the November 2008 election.

Clinton, the former first lady and one-time US senator, has proven to be an invaluable asset to Obama's administration over the past four years and is viewed as one of its most competent and popular players.

"She has done a great job. I would love for her to stay," said Obama, adding however that he also understands why she is leaving.

"I suspect that it is time for her to spend a little bit more time with her family," he said. "I could not be prouder of the work she has done."

Hillary Clinton is widely viewed as having taken a bullet for her boss earlier this month when she assumed the blame for the administration's clumsy handling of the September 11 attack on the US consulate in the Libyan city of Benghazi, which killed four Americans, including the American ambassador to Libya.

Obama has come under fire from his critics over the assault during which heavily-armed militants stormed the consulate compound and attacked an annex housing US personnel on the 11th anniversary of the Al-Qaeda attacks on the United States.

Obama's Republican rival in the November 6 vote, Mitt Romney, has accused the administration of giving a muddled response betraying a failed Middle East policy, while some Republican critics have gone so far as to allege a cover up.

Meanwhile Clinton's husband, former US president Bill Clinton, who has been one of Obama's most stalwart supporters on the campaign trail, gave a rousing speech in favor of the president during the Democratic National Convention in Charlotte, North Carolina last month.

That speech is credited with helping give Obama a sizable bump in the polls and a slight lead over Romney in the US presidential race.