John Kerry touted as successor to Hillary Clinton

Kerry's prospects soared last week when the UN ambassador, Susan Rice, a leading contender for the post, withdrew from consideration to avoid a fierce fight with Senate Republicans.

WASHINGTON // John Kerry stands tall as the good soldier to the US president, Barack Obama.

The Massachusetts senator has flown to Afghanistan and Pakistan numerous times to tamp down diplomatic disputes, spending hours drinking tea and taking walks with Hamid Karzai, the Afghan president, or engaging in delicate negotiations in Islamabad.

It is a highly unusual role for a Senate foreign relations committee chairman: the envoy with a special but undefined portfolio.

Mr Kerry, a Democrat, has pushed the White House's national security agenda in the Senate with mixed results. He successfully ensured ratification of a nuclear arms reduction treaty in 2010 and most recently failed to persuade Republicans to back a UN pact on the rights of the disabled.

Throughout this past election year, he skewered Mr Obama's Republican rival, Mitt Romney, at nearly every opportunity and was a vocal booster for the president's re-election. Mr Kerry memorably told delegates at the Democratic National Convention in August: "Ask Osama bin Laden if he's better off now than he was four years ago."

Mr Obama seems likely to reward all that work by nominating Mr Kerry, 69, perhaps in the coming days, to succeed Hillary Clinton as secretary of state, the nation's top diplomatic role. The prospects for the five-term senator soared last week when the UN ambassador, Susan Rice, a leading contender for the post, withdrew from consideration to avoid a fierce fight with Senate Republicans.

A Kerry nomination has been discussed with congressional leaders, and consultations between the White House and congressional Democrats have centred on the fate of his Senate seat, according to officials familiar with the situation. If the seat were in play, it could boost the prospects for the recently defeated Republican, Scott Brown, to win back a job in Washington.

At the same time, Mr Obama is considering one of Mr Kerry's former Senate colleagues, Republican Chuck Hagel of Nebraska, for the Pentagon's top job.

Senate colleagues in both parties said Mr Kerry's confirmation would be swift and near certain, a remarkable turnaround. Eight years ago, the GOP ridiculed Mr Kerry as a windsurfing flip-flopper as he tried and failed to unseat George W Bush.

John McCain, a Republican senator from Arizona and a former presidential candidate, has taken to jokingly referring to Kerry as "Mr Secretary".

Mr Kerry and Mr McCain have joined forces repeatedly during the past few decades.

Last year, the pair were outspoken in pushing for a no-fly zone over Libya as Muammar Qaddafi's forces attacked rebels and citizens.

Mr Kerry has travelled extensively for the administration: to Afghanistan in May as a strategic partnership agreement loomed large in the decade-plus war; and he was in Pakistan last year in the middle of a diplomatic crisis after Raymond Davis, a CIA-contracted American spy, was accused of killing two Pakistanis.

Chris Coons, a Democratic senator from Delaware and member of the foreign relations committee, recalled Mr Kerry's influence.

"I arrived in Islamabad I think five days after Ray Davis had been taken into a jail in the Punjab and was at very real risk of being hauled out of the jail and lynched," Mr Coons said.

"Senator Kerry was about to show up and negotiate on behalf of the administration. And it was clear that both the diplomats and the military folks we met with viewed him as a real man of credibility and experience who was likely to contribute meaningfully to those negotiations."

Mr Davis pleaded self-defence. After weeks of wrangling between the US and Pakistan, he was released in exchange for "blood money" paid to the dead men's relatives.

This year, Mr Kerry has presided over committee hearings on treaties and other major issues, but there has been little legislative work. He did not draw much attention to the committee, avoiding possible embarrassments for the administration in an election year.