US President Barack Obama is to pick a maverick former Republican senator as defence secretary later, amid a political backlash over the nomination.
Chuck Hagel would replace Leon Panetta at the Pentagon, but Mr Hagel's fellow Republicans have voiced criticism over the Nebraskan's views towards Israel.
White House officials also say Mr Obama will pick John Brennan as director of the Central Intelligence Agency.
Both appointments must be confirmed by the Senate.
The nominations are expected to be formally announced at the White House on Monday afternoon.
Along with Senator John Kerry, whom Mr Obama nominated last month to replace Hillary Clinton as secretary of state, Mr Hagel and Mr Brennan would help shape Mr Obama's second-term national security agenda.
'Worst possible message'
But the choice of Mr Hagel, a 66-year-old decorated Vietnam veteran, could prompt a Senate confirmation battle. Opponents say he is hostile to Israel and soft on Iran.
Mr Hagel has criticised discussion of a military strike by either the US or Israel against Iran and has advocated including Iran on future peace talks in Afghanistan.
Although no Republican lawmakers are threatening to block Mr Hagel's nomination, two influential senators have attacked him.
Mr Hagel made critical remarks against the Israel lobby in the US capital, quoted in a 2008 book by former state department official Aaron David Miller.
"The Jewish lobby intimidates a lot of people up here," Mr Hagel is quoted as having said. "I'm a United States senator. I'm not an Israeli senator."
Top Republican Senator Lindsey Graham told CNN that Mr Hagel would be "the most antagonistic defence secretary towards the state of Israel in our nation's history".
The second-ranking Senate Republican, John Cornyn of Texas, said in a statement that picking Mr Hagel would be "the worst possible message we could send to our friend Israel and the rest of our allies in the Middle East".
But White House officials say Mr Hagel's positions on these issues have been misrepresented, saying he voted to send billions in military assistance to Israel and has supported the imposition of multilateral sanctions on Tehran.
Mr Hagel has also been criticised by some Democrats for saying in 1998 that a nominee for an ambassador post was "openly, aggressively gay". He has since apologised for those comments.
If Mr Brennan is confirmed to lead the CIA, he will replace Gen David Petraeus, who resigned last year after admitting to an affair with his biographer.
A CIA veteran, Mr Brennan is currently Mr Obama's chief counter-terrorism adviser. The 57-year-old was heavily involved in the planning of the 2011 raid that killed Osama Bin Laden.
Although put forward for the role in 2008, Mr Brennan withdrew his name amid questions about his connection to interrogation techniques used during the administration of George W Bush.
"Brennan has the full trust and confidence of the president," a White House official, who spoke on condition of anonymity, told AFP news agency.
"Over the past four years, he has been involved in virtually all major national security issues and will be able to hit the ground running at CIA."