That would open up the Senate seat Kerry has held for nearly three decades. Recently defeated Republican Sen. Scott Brown might contest it.
Obama will announce Kerry's nomination from the White House Friday afternoon, said the official, who requested anonymity to discuss the president's decision before the announcement. Clinton was not expected to attend. The secretary fell and suffered a concussion last week, State Department officials said, and hasn't made public appearances since.
Word about Kerry's nomination — Washington's latest worst-kept secret — came at a somber and unusual time, with both the president and Kerry attending a memorial service for Democratic Sen. Daniel Inouye of Hawaii. At the same time, leaders of the nation's divided government were in utter limbo about how to head off the "fiscal cliff" looming Jan. 1.
Kerry's nomination could bring to a close what has become for the White House a contentious and distracting effort to find a new secretary of state.
Kerry was the Democratic nominee for president in 2004, losing a close election to incumbent George W. Bush. He's a decorated Vietnam veteran who was critical of the war when he returned to the U.S., even testifying in front of the Senate committee he eventually chaired.
Kerry's only other rival for the job, U.N. Ambassador Susan Rice, faced harsh criticism from congressional Republicans for her initial accounting of the deadly September attack on Americans in Benghazi, Libya. Obama vigorously defended Rice, a close friend and longtime adviser, but GOP senators dug in, threatening to hold up her nomination if the president tapped her for the post.
Rice withdrew her name from consideration last week, making Kerry all but certain to become the nominee. People familiar with the White House's decision-making said support within the administration was moving toward Kerry even before Rice pulled out.
The Cabinet nomination of Kerry, 69, is the first Obama has made since winning a second term, and the first piece in an extensive shuffle of his national security team. The president is also expected to nominate a new defense secretary soon to take over for retiring Leon Panetta and a new director of the Central Intelligence Agency to replace former spy chief David Petreaus, who resigned last month after admitting to an affair with his biographer.
The White House had hoped to introduce Obama's national security team in a package announcement. But those plans were scrapped as the fiscal cliff negotiations consumed the administration and questions arose about the front-runner for the Pentagon post, former Republican Sen. Chuck Hagel of Nebraska. Hagel has been dogged by questions about his support for Israel and where he stands on gay rights, with critics calling on him to repudiate a comment in 1998 that a former ambassadorial nominee was "openly, aggressively gay."
As the nation's top diplomat, Kerry will be tasked with not only executing the president's foreign policy objectives, but also shaping Obama's approach. The senator offered some insight into his world view on Thursday during a Senate Foreign Relations committee hearing he chaired on the deadly September attack on a U.S. consulate in Benghazi, Libya.
Kerry called on Congress to put enough money into America's foreign policy objectives and said doing so is an investment "in our long-term security and more often than not it saves far more expensive expenditures in dollars and lives for the conflicts that we failed to see or avoid."
And he emphasized the importance of U.S. diplomats being able to work freely in places like Benghazi, despite its dangers.
"There will always be a tension between the diplomatic imperative to get 'outside the wire' and the security standards that require our diplomats to work behind high walls," he said. "Our challenge is to strike a balance between the necessity of the mission, available resources and tolerance for risk."
Kerry, the son of a diplomat, has long sought the nation's top diplomatic post. Obama considered him for the job after the 2008 election before picking Clinton, his defeated rival for the Democratic presidential nomination, in a surprise move.
Since then, Obama has dispatched Kerry around the world on his behalf numerous times, particularly to tamp down diplomatic disputes in Afghanistan and Pakistan. He was also part of Obama's debate preparations team during the 2012 election, playing Republican challenger Mitt Romney in mock debates.
Kerry also won praise from Obama aides for his sharp national security-focused speech at the Democratic National Convention in August. He told delegates: "Ask Osama bin Laden if he's better off now than he was four years ago."
Before nominating Kerry, the White House consulted with congressional Democrats about the fate of the Senate seat he has held for five terms. Democrats have sought to assure the White House that the party has strong potential candidates in the state.
Kerry has pushed the White House's national security agenda in the Senate with mixed results. He ensured ratification of a nuclear arms reduction treaty in 2010 and most recently failed to persuade Republicans to back a U.N. pact on the rights of the disabled.
The senator was also outspoken in pushing for a 2011 no-fly zone over Libya as Moammar Gadhafi's forces attacked rebels and citizens.