WASHINGTON — US President Barack Obama may round out his new national security leadership team next week, with a nomination for defense secretary expected and a pick to lead the CIA possible.

Former Republican Sen. Chuck Hagel of Nebraska, said by a top House Democrat in a recent Newsmakers interview to have an “endemic hostility towards Israel,” is the front-runner for the top Pentagon post. Acting CIA Director Michael Morell and Obama counterterrorism adviser John Brennan are leading contenders to head the spy agency.

The public fight over the possible nomination of former senator Hagel as secretary of defense is quickly crystallizing into a battle over the “Israel lobby” and its ostensible influence on the US national agenda.

Pundits and several former officials who support Hagel have responded to criticism of the potential nominee by railing against “the brutal AIPAC-led campaign” against him — AIPAC has not expressed an opinion on the possible nomination — and suggested the battle against Hagel is being led by a “small minority of zealots” driven by their hardline views on Israel.

White House aides said the president has not made a final decision on either post and won’t until he returns from Hawaii, where he is vacationing with his family. Obama is due back in Washington Sunday morning.

Obama nominated Sen. John Kerry to replace Hillary Rodham Clinton as secretary of state in December, his first step in filling out his second term Cabinet and national security team. Kerry, as well as the nominees for the Pentagon and CIA, must be confirmed by the Senate.

Hagel, the former senator from Nebraska, is a contrarian Republican moderate and decorated Vietnam combat veteran who is likely to support a more rapid withdrawal of US troops from Afghanistan. If confirmed, Hagel would give Obama a whiff of bipartisanship in his Cabinet.

Even before his nomination, Hagel’s consideration for the top Pentagon job raised concerns among some of his former Senate colleagues, who questioned his pronouncements on Iraq, Israel and the Middle East. Troubling for some lawmakers are Hagel’s comments and actions on Israel, including his reference to the “Jewish lobby” in the United States.

Hagel has also been criticized for comments he made in 1998 about an openly gay nominee for an ambassadorship. In an interview with the Omaha World-Herald in 1998, Hagel said he believed that for a US ambassador, “it is an inhibiting factor to be gay” and referred to James C. Hormel as “openly, aggressively gay.” He has since apologized for those comments.

If nominated and confirmed, Hagel would replace current Defense Secretary Leon Panetta.

Morell has served as the CIA’s acting director since early November, after David Petraeus resigned after admitting to an affair with his biographer.

Brennan, Obama’s top counterterrorism adviser, worked at the CIA for 25 years, including a stint as station chief in Saudi Arabia. He also served as chief of staff to then CIA Director George Tenent from 1999 to 2001, when he was named the agency’s deputy executive director.