U.S. Senator John Kerry (D-MA) speaks during a news conference in Islamabad in this May 16, 2011 file photo. [Photo/Agencies]

WASHINGTON - US President Barack Obama has decided to nominate Massachusetts Senator John Kerry to be the next secretary of state, CNN and ABC News reported on Saturday, citing unnamed sources.

Kerry's nomination will not be announced for a variety of reasons, including the need to finalize the process and out of respect for the national mourning over Friday's school massacre in Newtown, Connecticut, ABC said.

CNN, citing an unnamed Democrat, said the nomination could be made public as early as next week.

Kerry, the Democratic presidential candidate in the 2004 election and chairman of the Senate Foreign Relations Committee, would replace Secretary of State Hillary Clinton if confirmed by the Senate.

Clinton has decided to step down from her job in the Obama administration.