President Obama on Monday nominated former Nebraska Republican Sen. Chuck Hagel to be his next defense secretary and counterterrorism adviser John Brennan to lead the Central Intelligence Agency, setting the stage for a fierce battle with Congress over the nominees.

Obama, joined by his Cabinet nominees in the East Room of the White House, called on the Senate to "promptly" confirm the duo. But behind the scenes, the White House is bracing for a fight, particularly over Hagel, a moderate Republican who has detractors on both sides of the aisle.

"Chuck Hagel is the leader that our troops deserve," Obama said. "He is an American patriot. He enlisted in our Army, volunteered for Vietnam, and first as a private, then as a sergeant, he served with honor alongside his own brother."

Republican critics immediately hit Hagel for being soft on Iran and hostile toward Israel, citing the former lawmaker's past dismissal of the "Jewish lobby" in Washington. Hagel also faces criticisms from the Left for once calling a nominee for an ambassadorship "openly, aggressively gay."

Looking to quell the growing criticism, Hagel on Monday told the Lincoln Journal Star, his hometown paper, that there is "not one shred of evidence that I'm anti-Israeli, not one [Senate] vote that matters that hurt Israel."

The White House enlisted several Jewish groups to publicly back Hagel. But they are up against a campaign-style opposition from Hagel's detractors.

Weekly Standard Editor Bill Kristol and his group, the Emergency Committee for Israel, started attacking Hagel in television ads and on a website before Obama even nominated him. [The Weekly Standard and The Washington Examiner are both owned by Clarity Media.]

With Republicans cooling on Hagel, his path to nomination will depend on whether Democrats unite behind a president who finally drew his line in the sand over a Cabinet post. Obama chose not to nominate U.N. Ambassador Susan Rice for secretary of state in the face of Republican resistance.

Many Democrats on Monday praised Hagel's war service but stopped short of giving him a full-throated endorsement.

"I will do all I can to ensure the confirmation hearing addresses important questions regarding the future of our military, the current budgetary challenges facing the country and other important security issues such as U.S. policy towards Iran," said Sen. Tim Kaine, D-Va., who did not commit to voting for Hagel.

With Brennan, Obama tapped a 25-year CIA veteran who spearheaded the administration's counterterrorism efforts in recent years.

However, Brennan has been under fire because of his ties to the interrogation methods -- including waterboarding -- approved by former President George W. Bush and for Brennan's role in the heightened use of armed drones during Obama's first term.

"I have many questions and concerns about his nomination, especially what role he played in the so-called enhanced interrogation programs while serving at the CIA during the last administration, as well as his public defense of those programs," said Sen. John McCain, R-Ariz., a former prisoner of war who was tortured by the Vietnamese.

Obama is looking for less drama at the CIA after Gen. David Petraeus resigned the post following an extramarital affair.

Obama will soon announce his next Treasury secretary. His chief of staff, Jacob Lew, is the front-runner for the position.