US President Barack Obama is leaning toward picking Caroline Kennedy to be the next US ambassador to Japan, a source familiar with the process said on Monday.

The 55-year-old daughter of assassinated former president John Kennedy would be the first female US ambassador to Japan.

She was one of the earliest backers of Obama in his first presidential campaign in 2008, and her endorsement was significant in helping him defeat then-US senator Hillary Clinton in the Democratic presidential primary that year.

The author and lawyer serves on the board of several nonprofit organizations. She would replace the current ambassador, John Roos, the former CEO of Silicon Valley-based law firm Wilson Sonsini Goodrich & Rosati.

White House spokesman Jay Carney declined to comment on whether Obama had settled on Kennedy for the post to represent the United States in Japan, one of Washington's top Asia allies.

"I have no personnel announcements to make," he said.

The Japan ambassadorship is an important diplomatic posting for the US.

Advanced stages

Kennedy is in the advanced stages of the selection process, an administration official told AFP. Earlier on Monday, both The Washington Post and The New York Times reported that she was actively being vetted for the appointment.

Kennedy would fit the long tradition of presidents naming high-profile envoys to key US ally Japan, who have included former vice-president Walter Mondale and former senators Mike Mansfield and Howard Baker.

But she would also take up the post at a time of great diplomatic peril, given the fierce military threats by the Democratic People's Republic of Korea against the US and its key regional partners.

The crises had prompted some diplomatic observers in Washington in recent weeks to suggest that Kennedy could be passed over for a more experienced diplomatic hand.

But Kennedy's chances may have been enhanced by the arrival as secretary of state of John Kerry, who was close to Caroline Kennedy's uncle, Edward Kennedy.

While politics and public service runs in Kennedy's blood, she has long resisted the public role of her father; his brothers, former senators Robert Kennedy and Edward Kennedy, and many of their progeny.

Japan enthusiastic

The mooted appointment of Kennedy to the high-profile post of ambassador to Japan was greeted enthusiastically in Japan on Tuesday.

Japan's top government spokesman said it would be "big news" for the country if she gets the nomination.

"The late president Kennedy was a figure familiar to many Japanese," Yoshihide Suga said at a regular news conference on Tuesday.

"It would be big news, and would deepen people's feeling of friendliness" to the US, he said, adding that he would refrain from commenting further until a final decision was made.

For a time in late 2008 and early 2009, Kennedy toyed with the idea of running for the New York Democratic Senate seat vacated by Clinton when Clinton became Obama's first-term secretary of state.

Obama backer

But the wealthy Kennedy pulled out of the running after a rough political ride amid claims she was being foisted upon the New York electorate with nothing but her family name as a qualification.

Kennedy, whom many US citizens remember as a tragic little girl at her father's 1963 funeral at Arlington National Cemetery, caused a sensation in 2008, and fury in Clinton circles, when she broke from her intensely private world to back Obama.

In a New York Times column titled A President Like My Father, Kennedy wrote of never having seen a president who matched up to the way people still talked about JFK.

Now, she said, "I believe I have found a man who could be that president."

Reuters - AFP