WASHINGTON, Dec 21: US President Barack Obama nominated on Friday Senator John Kerry as the next secretary of state, hoping for a smooth confirmation by the Senate.

“I am very proud to announce my choice for America's next secretary of state, John Kerry,” during a joint appearance with Senator Kerry in the Roosevelt Room of the White House.

“He understands that we have a responsibility to use American power wisely.”

If confirmed by the Senate, Mr Kerry will replace outgoing Secretary of State Hillary Clinton as head of the State Department. Mrs Clinton has said repeatedly that she plans to leave early next year.

Referring to the difficult task ahead for the senator, President Obama noted that “an uncertain world will continue to test our nation” but he said he was confident that Mr Kerry was the right man for this job.

“In a sense, John’s entire life has prepared him for this role,” Mr Obama said. “He is not going to need a lot of on-the-job training.”

The announcement was made just steps from the Oval Office that Senator Kerry tried to reach himself as their party’s 2004 presidential nominee.

Senator Kerry’s wife, Teresa Heinz Kerry, stood next to Vice President Joe Biden as the president noted her personal history as an immigrant from Africa.

Senator Kerry did not speak and left the room with the president and the vice president as reporters shouted questions at them.

Mrs Clinton did not attend as she recovers from a concussion after fainting last week following a bout with a virus. President Obama added that the outgoing secretary “could not be more excited about the announcement that I am making”. She was Mr Kerry’s colleague in the Senate and two often worked together on foreign policy issues.

The White House has also indicated that President Obama may choose a former Republican senator, Chuck Hagel, as his next secretary of defence.

The decision to give two key cabinet posts to lawmakers who support Mr Obama’s plans for reducing US military involvement is interpreted in the US capital as indicating an early US withdrawal from Afghanistan.

The US media, quoting White House sources, reported that President Obama chose Mr Kerry because he is a long-time political ally and also because as a five-term senator he is likely to sail through confirmation hearings.

Speculation of Senator Kerry’s appointment has been widespread since Mr Obama’s first choice, America’s UN Ambassador Susan Rice, withdrew her name from consideration last week.

Senate Republicans had pledged to oppose her appointment because of her handling of the September attack on the US consulate in Benghazi, Libya.

As chairman of the Senate Foreign Relations Committee, Senator Kerry often acted as Mr Obama’s unofficial envoy for trouble spots, particularly Pakistan and Afghanistan. He also played a key role in passing a multi-year aid bill for Pakistan.

Like Senator Kerry, Mr Hagel also has a close personal relationship with Mr Obama forged when both were in the Senate.

Mr Hagel would succeed Defence Secretary Leon Panetta.

An announcement is expected early week.